RocksDB

java.lang.Object
- org.rocksdb.AbstractNativeReference
- - org.rocksdb.AbstractImmutableNativeReference
  - - org.rocksdb.RocksObject
    - - org.rocksdb.RocksDB

所有已实现的接口:

java.lang.AutoCloseable

直接已知子类:

OptimisticTransactionDB, TransactionDB, TtlDB
```
public class RocksDB
extends RocksObject
```
A RocksDB is a persistent ordered map from keys to values. It is safe for concurrent access from multiple threads without any external synchronization. All methods of this class could potentially throw RocksDBException, which indicates sth wrong at the RocksDB library side and the call failed.

嵌套类概要

嵌套类
限定符和类型类和说明

static class RocksDB.CountAndSize

static class RocksDB.LiveFiles

static class RocksDB.Version

嵌套类
限定符和类型	类和说明
`static class`	`RocksDB.CountAndSize`
`static class`	`RocksDB.LiveFiles`
`static class`	`RocksDB.Version`

字段概要

字段
限定符和类型字段和说明

static byte[] DEFAULT_COLUMN_FAMILY

static int NOT_FOUND

protected DBOptionsInterface<?> options_
- 从类继承的字段 org.rocksdb.RocksObject
  nativeHandle_
- 从类继承的字段 org.rocksdb.AbstractImmutableNativeReference
  owningHandle_

字段
限定符和类型	字段和说明
`static byte[]`	`DEFAULT_COLUMN_FAMILY`
`static int`	`NOT_FOUND`
`protected DBOptionsInterface<?>`	`options_`

构造器概要

构造器
限定符构造器和说明

protected RocksDB(long nativeHandle)
Private constructor.

构造器
限定符	构造器和说明
`protected`	`RocksDB(long nativeHandle)` Private constructor.

方法概要

所有方法静态方法实例方法具体方法
限定符和类型	方法和说明
`void`	`cancelAllBackgroundWork(boolean wait)` This function will cancel all currently running background processes.
`void`	`close()` This is similar to `closeE()` except that it silently ignores any errors.
`void`	`closeE()` This is similar to `close()` except that it throws an exception if any error occurs.
`java.util.List<java.lang.String>`	`compactFiles(CompactionOptions compactionOptions, ColumnFamilyHandle columnFamilyHandle, java.util.List<java.lang.String> inputFileNames, int outputLevel, int outputPathId, CompactionJobInfo compactionJobInfo)` Takes a list of files specified by file names and compacts them to the specified level.
`java.util.List<java.lang.String>`	`compactFiles(CompactionOptions compactionOptions, java.util.List<java.lang.String> inputFileNames, int outputLevel, int outputPathId, CompactionJobInfo compactionJobInfo)` Takes a list of files specified by file names and compacts them to the specified level.
`void`	`compactRange()` Range compaction of database.
`void`	`compactRange(byte[] begin, byte[] end)` Range compaction of database.
`void`	`compactRange(ColumnFamilyHandle columnFamilyHandle)` Range compaction of column family.
`void`	`compactRange(ColumnFamilyHandle columnFamilyHandle, byte[] begin, byte[] end)` Range compaction of column family.
`void`	`compactRange(ColumnFamilyHandle columnFamilyHandle, byte[] begin, byte[] end, CompactRangeOptions compactRangeOptions)` Range compaction of column family.
`void`	`continueBackgroundWork()` Resumes background work which was suspended by previously calling `pauseBackgroundWork()`
`java.util.List<ColumnFamilyHandle>`	`createColumnFamilies(ColumnFamilyOptions columnFamilyOptions, java.util.List<byte[]> columnFamilyNames)` Bulk create column families with the same column family options.
`java.util.List<ColumnFamilyHandle>`	`createColumnFamilies(java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors)` Bulk create column families with the same column family options.
`ColumnFamilyHandle`	`createColumnFamily(ColumnFamilyDescriptor columnFamilyDescriptor)` Creates a new column family with the name columnFamilyName and allocates a ColumnFamilyHandle within an internal structure.
`void`	`delete(byte[] key)` Delete the database entry (if any) for "key".
`void`	`delete(byte[] key, int offset, int len)` Delete the database entry (if any) for "key".
`void`	`delete(ColumnFamilyHandle columnFamilyHandle, byte[] key)` Delete the database entry (if any) for "key".
`void`	`delete(ColumnFamilyHandle columnFamilyHandle, byte[] key, int offset, int len)` Delete the database entry (if any) for "key".
`void`	`delete(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpt, byte[] key)` Delete the database entry (if any) for "key".
`void`	`delete(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpt, byte[] key, int offset, int len)` Delete the database entry (if any) for "key".
`void`	`delete(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpt, java.nio.ByteBuffer key)` Delete the database entry (if any) for "key".
`void`	`delete(WriteOptions writeOpt, byte[] key)` Delete the database entry (if any) for "key".
`void`	`delete(WriteOptions writeOpt, byte[] key, int offset, int len)` Delete the database entry (if any) for "key".
`void`	`delete(WriteOptions writeOpt, java.nio.ByteBuffer key)` Delete the database entry (if any) for "key".
`void`	`deleteFile(java.lang.String name)` Delete the file name from the db directory and update the internal state to reflect that.
`void`	`deleteFilesInRanges(ColumnFamilyHandle columnFamily, java.util.List<byte[]> ranges, boolean includeEnd)` Delete files in multiple ranges at once.
`void`	`deleteRange(byte[] beginKey, byte[] endKey)` Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error.
`void`	`deleteRange(ColumnFamilyHandle columnFamilyHandle, byte[] beginKey, byte[] endKey)` Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error.
`void`	`deleteRange(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpt, byte[] beginKey, byte[] endKey)` Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error.
`void`	`deleteRange(WriteOptions writeOpt, byte[] beginKey, byte[] endKey)` Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error.
`void`	`destroyColumnFamilyHandle(ColumnFamilyHandle columnFamilyHandle)` Deletes native column family handle of given `ColumnFamilyHandle` Java object and removes reference from `ownedColumnFamilyHandles`.
`static void`	`destroyDB(java.lang.String path, Options options)` Static method to destroy the contents of the specified database.
`void`	`disableFileDeletions()` Prevent file deletions.
`protected void`	`disposeInternal(long handle)`
`void`	`dropColumnFamilies(java.util.List<ColumnFamilyHandle> columnFamilies)`
`void`	`dropColumnFamily(ColumnFamilyHandle columnFamilyHandle)` Drops the column family specified by `columnFamilyHandle`.
`void`	`enableAutoCompaction(java.util.List<ColumnFamilyHandle> columnFamilyHandles)` Enable automatic compactions for the given column families if they were previously disabled.
`void`	`enableFileDeletions(boolean force)` Allow compactions to delete obsolete files.
`void`	`endTrace()` Stop tracing DB operations.
`void`	`flush(FlushOptions flushOptions)` Flush all memory table data.
`void`	`flush(FlushOptions flushOptions, ColumnFamilyHandle columnFamilyHandle)` Flush all memory table data.
`void`	`flush(FlushOptions flushOptions, java.util.List<ColumnFamilyHandle> columnFamilyHandles)` Flushes multiple column families.
`void`	`flushWal(boolean sync)` Flush the WAL memory buffer to the file.
`byte[]`	`get(byte[] key)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(byte[] key, byte[] value)` Get the value associated with the specified key within column family*
`byte[]`	`get(byte[] key, int offset, int len)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Get the value associated with the specified key within column family*
`byte[]`	`get(ColumnFamilyHandle columnFamilyHandle, byte[] key)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(ColumnFamilyHandle columnFamilyHandle, byte[] key, byte[] value)` Get the value associated with the specified key within column family.
`byte[]`	`get(ColumnFamilyHandle columnFamilyHandle, byte[] key, int offset, int len)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(ColumnFamilyHandle columnFamilyHandle, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Get the value associated with the specified key within column family.
`byte[]`	`get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt, byte[] key)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt, byte[] key, byte[] value)` Get the value associated with the specified key within column family.
`byte[]`	`get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt, byte[] key, int offset, int len)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Get the value associated with the specified key within column family.
`int`	`get(ColumnFamilyHandle columnFamilyHandle, ReadOptions opt, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` Get the value associated with the specified key within column family.
`byte[]`	`get(ReadOptions opt, byte[] key)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(ReadOptions opt, byte[] key, byte[] value)` Get the value associated with the specified key.
`byte[]`	`get(ReadOptions opt, byte[] key, int offset, int len)` The simplified version of get which returns a new byte array storing the value associated with the specified input key if any.
`int`	`get(ReadOptions opt, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Get the value associated with the specified key.
`int`	`get(ReadOptions opt, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` Get the value associated with the specified key within column family.
`long`	`getAggregatedLongProperty(java.lang.String property)` Return sum of the getLongProperty of all the column families Note: As the returned property is of type `uint64_t` on C++ side the returning value can be negative because Java supports in Java 7 only signed long values.
`RocksDB.CountAndSize`	`getApproximateMemTableStats(ColumnFamilyHandle columnFamilyHandle, Range range)` This method is similar to `getApproximateSizes(ColumnFamilyHandle, List, SizeApproximationFlag...)`, except that it returns approximate number of records and size in memtables.
`RocksDB.CountAndSize`	`getApproximateMemTableStats(Range range)` This method is similar to `getApproximateSizes(ColumnFamilyHandle, List, SizeApproximationFlag...)`, except that it returns approximate number of records and size in memtables.
`long[]`	`getApproximateSizes(ColumnFamilyHandle columnFamilyHandle, java.util.List<Range> ranges, SizeApproximationFlag... sizeApproximationFlags)` Get the approximate file system space used by keys in each range.
`long[]`	`getApproximateSizes(java.util.List<Range> ranges, SizeApproximationFlag... sizeApproximationFlags)` Get the approximate file system space used by keys in each range for the default column family.
`ColumnFamilyMetaData`	`getColumnFamilyMetaData()` Obtains the meta data of the default column family of the DB.
`ColumnFamilyMetaData`	`getColumnFamilyMetaData(ColumnFamilyHandle columnFamilyHandle)` Obtains the meta data of the specified column family of the DB.
`MutableDBOptions.MutableDBOptionsBuilder`	`getDBOptions()` Get the database options
`ColumnFamilyHandle`	`getDefaultColumnFamily()` Gets the handle for the default column family
`Env`	`getEnv()` Get the Env object from the DB
`long`	`getLatestSequenceNumber()` The sequence number of the most recent transaction.
`RocksDB.LiveFiles`	`getLiveFiles()` Retrieve the list of all files in the database after flushing the memtable.
`RocksDB.LiveFiles`	`getLiveFiles(boolean flushMemtable)` Retrieve the list of all files in the database.
`java.util.List<LiveFileMetaData>`	`getLiveFilesMetaData()` Gets a list of all table files metadata.
`long`	`getLongProperty(ColumnFamilyHandle columnFamilyHandle, java.lang.String property)` Similar to GetProperty(), but only works for a subset of properties whose return value is a numerical value.
`long`	`getLongProperty(java.lang.String property)` Similar to GetProperty(), but only works for a subset of properties whose return value is a numerical value.
`java.util.Map<java.lang.String,java.lang.String>`	`getMapProperty(ColumnFamilyHandle columnFamilyHandle, java.lang.String property)` Gets a property map.
`java.util.Map<java.lang.String,java.lang.String>`	`getMapProperty(java.lang.String property)` Gets a property map.
`java.lang.String`	`getName()` Get DB name -- the exact same name that was provided as an argument to as path to `open(Options, String)`.
`MutableColumnFamilyOptions.MutableColumnFamilyOptionsBuilder`	`getOptions()` Default column family options
`MutableColumnFamilyOptions.MutableColumnFamilyOptionsBuilder`	`getOptions(ColumnFamilyHandle columnFamilyHandle)` Get the options for the column family handle
`java.util.Map<java.lang.String,TableProperties>`	`getPropertiesOfAllTables()` Get the properties of all tables in the default column family.
`java.util.Map<java.lang.String,TableProperties>`	`getPropertiesOfAllTables(ColumnFamilyHandle columnFamilyHandle)` Get the properties of all tables.
`java.util.Map<java.lang.String,TableProperties>`	`getPropertiesOfTablesInRange(ColumnFamilyHandle columnFamilyHandle, java.util.List<Range> ranges)` Get the properties of tables in range.
`java.util.Map<java.lang.String,TableProperties>`	`getPropertiesOfTablesInRange(java.util.List<Range> ranges)` Get the properties of tables in range for the default column family.
`java.lang.String`	`getProperty(ColumnFamilyHandle columnFamilyHandle, java.lang.String property)` DB implements can export properties about their state via this method on a per column family level.
`java.lang.String`	`getProperty(java.lang.String property)` DB implementations can export properties about their state via this method.
`Snapshot`	`getSnapshot()` Return a handle to the current DB state.
`java.util.List<LogFile>`	`getSortedWalFiles()` Retrieve the sorted list of all wal files with earliest file first.
`TransactionLogIterator`	`getUpdatesSince(long sequenceNumber)` Returns an iterator that is positioned at a write-batch containing seq_number.
`void`	`ingestExternalFile(ColumnFamilyHandle columnFamilyHandle, java.util.List<java.lang.String> filePathList, IngestExternalFileOptions ingestExternalFileOptions)` ingestExternalFile will load a list of external SST files (1) into the DB We will try to find the lowest possible level that the file can fit in, and ingest the file into this level (2).
`void`	`ingestExternalFile(java.util.List<java.lang.String> filePathList, IngestExternalFileOptions ingestExternalFileOptions)` ingestExternalFile will load a list of external SST files (1) into the DB We will try to find the lowest possible level that the file can fit in, and ingest the file into this level (2).
`boolean`	`keyMayExist(byte[] key, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(byte[] key, int offset, int len, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(java.nio.ByteBuffer key)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`KeyMayExist`	`keyMayExist(java.nio.ByteBuffer key, java.nio.ByteBuffer value)` If the key definitely does not exist in the database, then this method returns `KeyMayExist.KeyMayExistEnum.kNotExist`, otherwise if it can with best effort retreive the value, it returns `KeyMayExist.KeyMayExistEnum.kExistsWithValue` otherwise it returns `KeyMayExist.KeyMayExistEnum.kExistsWithoutValue`.
`boolean`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, byte[] key, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, byte[] key, int offset, int len, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, java.nio.ByteBuffer key)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`KeyMayExist`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` If the key definitely does not exist in the database, then this method returns `KeyMayExist.KeyMayExistEnum.kNotExist`, otherwise if it can with best effort retreive the value, it returns `KeyMayExist.KeyMayExistEnum.kExistsWithValue` otherwise it returns `KeyMayExist.KeyMayExistEnum.kExistsWithoutValue`.
`boolean`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, ReadOptions readOptions, byte[] key, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, ReadOptions readOptions, byte[] key, int offset, int len, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, ReadOptions readOptions, java.nio.ByteBuffer key)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`KeyMayExist`	`keyMayExist(ColumnFamilyHandle columnFamilyHandle, ReadOptions readOptions, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` If the key definitely does not exist in the database, then this method returns `KeyMayExist.KeyMayExistEnum.kNotExist`, otherwise if it can with best effort retreive the value, it returns `KeyMayExist.KeyMayExistEnum.kExistsWithValue` otherwise it returns `KeyMayExist.KeyMayExistEnum.kExistsWithoutValue`.
`boolean`	`keyMayExist(ReadOptions readOptions, byte[] key, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(ReadOptions readOptions, byte[] key, int offset, int len, Holder<byte[]> valueHolder)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`boolean`	`keyMayExist(ReadOptions readOptions, java.nio.ByteBuffer key)` If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist.
`KeyMayExist`	`keyMayExist(ReadOptions readOptions, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` If the key definitely does not exist in the database, then this method returns `KeyMayExist.KeyMayExistEnum.kNotExist`, otherwise if it can with best effort retreive the value, it returns `KeyMayExist.KeyMayExistEnum.kExistsWithValue` otherwise it returns `KeyMayExist.KeyMayExistEnum.kExistsWithoutValue`.
`int`	`level0StopWriteTrigger()` Number of files in level-0 that would stop writes.
`int`	`level0StopWriteTrigger(ColumnFamilyHandle columnFamilyHandle)` Number of files in level-0 that would stop writes.
`static java.util.List<byte[]>`	`listColumnFamilies(Options options, java.lang.String path)` Static method to determine all available column families for a rocksdb database identified by path
`static void`	`loadLibrary()` Loads the necessary library files.
`static void`	`loadLibrary(java.util.List<java.lang.String> paths)` Tries to load the necessary library files from the given list of directories.
`int`	`maxMemCompactionLevel()` Maximum level to which a new compacted memtable is pushed if it does not create overlap.
`int`	`maxMemCompactionLevel(ColumnFamilyHandle columnFamilyHandle)` Maximum level to which a new compacted memtable is pushed if it does not create overlap.
`void`	`merge(byte[] key, byte[] value)` Add merge operand for key/value pair.
`void`	`merge(byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Add merge operand for key/value pair.
`void`	`merge(ColumnFamilyHandle columnFamilyHandle, byte[] key, byte[] value)` Add merge operand for key/value pair in a ColumnFamily.
`void`	`merge(ColumnFamilyHandle columnFamilyHandle, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Add merge operand for key/value pair in a ColumnFamily.
`void`	`merge(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpts, byte[] key, byte[] value)` Add merge operand for key/value pair.
`void`	`merge(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpts, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Add merge operand for key/value pair.
`void`	`merge(WriteOptions writeOpts, byte[] key, byte[] value)` Add merge operand for key/value pair.
`void`	`merge(WriteOptions writeOpts, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Add merge operand for key/value pair.
`java.util.List<byte[]>`	`multiGetAsList(java.util.List<byte[]> keys)` Takes a list of keys, and returns a list of values for the given list of keys.
`java.util.List<byte[]>`	`multiGetAsList(java.util.List<ColumnFamilyHandle> columnFamilyHandleList, java.util.List<byte[]> keys)` Returns a list of values for the given list of keys.
`java.util.List<byte[]>`	`multiGetAsList(ReadOptions opt, java.util.List<byte[]> keys)` Returns a list of values for the given list of keys.
`java.util.List<byte[]>`	`multiGetAsList(ReadOptions opt, java.util.List<ColumnFamilyHandle> columnFamilyHandleList, java.util.List<byte[]> keys)` Returns a list of values for the given list of keys.
`java.util.List<ByteBufferGetStatus>`	`multiGetByteBuffers(java.util.List<java.nio.ByteBuffer> keys, java.util.List<java.nio.ByteBuffer> values)` Fetches a list of values for the given list of keys, all from the default column family.
`java.util.List<ByteBufferGetStatus>`	`multiGetByteBuffers(java.util.List<ColumnFamilyHandle> columnFamilyHandleList, java.util.List<java.nio.ByteBuffer> keys, java.util.List<java.nio.ByteBuffer> values)` Fetches a list of values for the given list of keys.
`java.util.List<ByteBufferGetStatus>`	`multiGetByteBuffers(ReadOptions readOptions, java.util.List<java.nio.ByteBuffer> keys, java.util.List<java.nio.ByteBuffer> values)` Fetches a list of values for the given list of keys, all from the default column family.
`java.util.List<ByteBufferGetStatus>`	`multiGetByteBuffers(ReadOptions readOptions, java.util.List<ColumnFamilyHandle> columnFamilyHandleList, java.util.List<java.nio.ByteBuffer> keys, java.util.List<java.nio.ByteBuffer> values)` Fetches a list of values for the given list of keys.
`RocksIterator`	`newIterator()` Return a heap-allocated iterator over the contents of the database.
`RocksIterator`	`newIterator(ColumnFamilyHandle columnFamilyHandle)` Return a heap-allocated iterator over the contents of a ColumnFamily.
`RocksIterator`	`newIterator(ColumnFamilyHandle columnFamilyHandle, ReadOptions readOptions)` Return a heap-allocated iterator over the contents of a ColumnFamily.
`RocksIterator`	`newIterator(ReadOptions readOptions)` Return a heap-allocated iterator over the contents of the database.
`java.util.List<RocksIterator>`	`newIterators(java.util.List<ColumnFamilyHandle> columnFamilyHandleList)` Returns iterators from a consistent database state across multiple column families.
`java.util.List<RocksIterator>`	`newIterators(java.util.List<ColumnFamilyHandle> columnFamilyHandleList, ReadOptions readOptions)` Returns iterators from a consistent database state across multiple column families.
`int`	`numberLevels()` Number of levels used for this DB.
`int`	`numberLevels(ColumnFamilyHandle columnFamilyHandle)` Number of levels used for a column family in this DB.
`static RocksDB`	`open(DBOptions options, java.lang.String path, java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors, java.util.List<ColumnFamilyHandle> columnFamilyHandles)` The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the specified options and db path and a list of column family names.
`static RocksDB`	`open(Options options, java.lang.String path)` The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the specified options and db path.
`static RocksDB`	`open(java.lang.String path)` The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the default options w/ createIfMissing set to true.
`static RocksDB`	`open(java.lang.String path, java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors, java.util.List<ColumnFamilyHandle> columnFamilyHandles)` The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the specified options and db path and a list of column family names.
`static RocksDB`	`openAsSecondary(DBOptions options, java.lang.String path, java.lang.String secondaryPath, java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors, java.util.List<ColumnFamilyHandle> columnFamilyHandles)` Open DB as secondary instance with column families.
`static RocksDB`	`openAsSecondary(Options options, java.lang.String path, java.lang.String secondaryPath)` Open DB as secondary instance with only the default column family.
`static RocksDB`	`openReadOnly(DBOptions options, java.lang.String path, java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors, java.util.List<ColumnFamilyHandle> columnFamilyHandles)` The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
`static RocksDB`	`openReadOnly(DBOptions options, java.lang.String path, java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors, java.util.List<ColumnFamilyHandle> columnFamilyHandles, boolean errorIfWalFileExists)` The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
`static RocksDB`	`openReadOnly(Options options, java.lang.String path)` The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
`static RocksDB`	`openReadOnly(Options options, java.lang.String path, boolean errorIfWalFileExists)` The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
`static RocksDB`	`openReadOnly(java.lang.String path)` The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the default options.
`static RocksDB`	`openReadOnly(java.lang.String path, java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors, java.util.List<ColumnFamilyHandle> columnFamilyHandles)` The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the default options.
`void`	`pauseBackgroundWork()` This function will wait until all currently running background processes finish.
`void`	`promoteL0(ColumnFamilyHandle columnFamilyHandle, int targetLevel)` Promote L0.
`void`	`promoteL0(int targetLevel)` Promote L0 for the default column family.
`void`	`put(byte[] key, byte[] value)` Set the database entry for "key" to "value".
`void`	`put(byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Set the database entry for "key" to "value".
`void`	`put(ColumnFamilyHandle columnFamilyHandle, byte[] key, byte[] value)` Set the database entry for "key" to "value" in the specified column family.
`void`	`put(ColumnFamilyHandle columnFamilyHandle, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Set the database entry for "key" to "value" in the specified column family.
`void`	`put(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpts, byte[] key, byte[] value)` Set the database entry for "key" to "value" for the specified column family.
`void`	`put(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpts, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Set the database entry for "key" to "value" for the specified column family.
`void`	`put(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpts, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` Set the database entry for "key" to "value" for the specified column family.
`void`	`put(WriteOptions writeOpts, byte[] key, byte[] value)` Set the database entry for "key" to "value".
`void`	`put(WriteOptions writeOpts, byte[] key, int offset, int len, byte[] value, int vOffset, int vLen)` Set the database entry for "key" to "value".
`void`	`put(WriteOptions writeOpts, java.nio.ByteBuffer key, java.nio.ByteBuffer value)` Set the database entry for "key" to "value".
`void`	`releaseSnapshot(Snapshot snapshot)` Release a previously acquired snapshot.
`void`	`resetStats()` Reset internal stats for DB and all column families.
`static RocksDB.Version`	`rocksdbVersion()`
`void`	`setDBOptions(MutableDBOptions mutableDBoptions)` Set the options for the column family handle.
`void`	`setOptions(ColumnFamilyHandle columnFamilyHandle, MutableColumnFamilyOptions mutableColumnFamilyOptions)` Change the options for the column family handle.
`void`	`setOptions(MutableColumnFamilyOptions mutableColumnFamilyOptions)` Change the options for the default column family handle.
`void`	`singleDelete(byte[] key)` Remove the database entry for `key`.
`void`	`singleDelete(ColumnFamilyHandle columnFamilyHandle, byte[] key)` Remove the database entry for `key`.
`void`	`singleDelete(ColumnFamilyHandle columnFamilyHandle, WriteOptions writeOpt, byte[] key)` Remove the database entry for `key`.
`void`	`singleDelete(WriteOptions writeOpt, byte[] key)` Remove the database entry for `key`.
`void`	`startTrace(TraceOptions traceOptions, AbstractTraceWriter traceWriter)` Trace DB operations.
`protected void`	`storeOptionsInstance(DBOptionsInterface<?> options)`
`Range`	`suggestCompactRange()` Suggest the range to compact for the default column family.
`Range`	`suggestCompactRange(ColumnFamilyHandle columnFamilyHandle)` Suggest the range to compact.
`void`	`syncWal()` Sync the WAL.
`void`	`tryCatchUpWithPrimary()` Make the secondary instance catch up with the primary by tailing and replaying the MANIFEST and WAL of the primary.
`void`	`verifyChecksum()` Verify checksum
`void`	`write(WriteOptions writeOpts, WriteBatch updates)` Apply the specified updates to the database.
`void`	`write(WriteOptions writeOpts, WriteBatchWithIndex updates)` Apply the specified updates to the database.

从类继承的方法 org.rocksdb.RocksObject
disposeInternal, getNativeHandle

从类继承的方法 org.rocksdb.AbstractImmutableNativeReference
disOwnNativeHandle, isOwningHandle

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - DEFAULT_COLUMN_FAMILY
```
public static final byte[] DEFAULT_COLUMN_FAMILY
```
  - NOT_FOUND
```
public static final int NOT_FOUND
```
    另请参阅:
    
    常量字段值
  - options_
```
protected DBOptionsInterface<?> options_
```
- 构造器详细资料
  - RocksDB
```
protected RocksDB(long nativeHandle)
```
    Private constructor.
    
    参数:
    
    nativeHandle - The native handle of the C++ RocksDB object
- 方法详细资料
  - loadLibrary
```
public static void loadLibrary()
```
    Loads the necessary library files. Calling this method twice will have no effect. By default the method extracts the shared library for loading at java.io.tmpdir, however, you can override this temporary location by setting the environment variable ROCKSDB_SHAREDLIB_DIR.
  - loadLibrary
```
public static void loadLibrary(java.util.List<java.lang.String> paths)
```
    Tries to load the necessary library files from the given list of directories.
    
    参数:
    
    paths - a list of strings where each describes a directory of a library.
  - rocksdbVersion
```
public static RocksDB.Version rocksdbVersion()
```
  - open
```
public static RocksDB open(java.lang.String path)
                    throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the default options w/ createIfMissing set to true.
    
    参数:
    
    path - the path to the rocksdb.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    Options.setCreateIfMissing(boolean)
  - open
```
public static RocksDB open(java.lang.String path,
                           java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                           java.util.List<ColumnFamilyHandle> columnFamilyHandles)
                    throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the specified options and db path and a list of column family names.
    If opened in read write mode every existing column family name must be passed within the list to this method.
    
    If opened in read-only mode only a subset of existing column families must be passed to this method.
    
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly, then this options instance will be GC'd automatically
    
    ColumnFamily handles are disposed when the RocksDB instance is disposed.
    
    参数:
    
    path - the path to the rocksdb.
    
    columnFamilyDescriptors - list of column family descriptors
    
    columnFamilyHandles - will be filled with ColumnFamilyHandle instances on open.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    DBOptions.setCreateIfMissing(boolean)
  - open
```
public static RocksDB open(Options options,
                           java.lang.String path)
                    throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the specified options and db path.
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly, then this options instance will be GC'd automatically.
    
    Options instance can be re-used to open multiple DBs if DB statistics is not used. If DB statistics are required, then its recommended to open DB with new Options instance as underlying native statistics instance does not use any locks to prevent concurrent updates.
    
    参数:
    
    options - Options instance.
    
    path - the path to the rocksdb.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    Options.setCreateIfMissing(boolean)
  - open
```
public static RocksDB open(DBOptions options,
                           java.lang.String path,
                           java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                           java.util.List<ColumnFamilyHandle> columnFamilyHandles)
                    throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance given the path to the database using the specified options and db path and a list of column family names.
    If opened in read write mode every existing column family name must be passed within the list to this method.
    
    If opened in read-only mode only a subset of existing column families must be passed to this method.
    
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly, then this options instance will be GC'd automatically.
    
    Options instance can be re-used to open multiple DBs if DB statistics is not used. If DB statistics are required, then its recommended to open DB with new Options instance as underlying native statistics instance does not use any locks to prevent concurrent updates.
    
    ColumnFamily handles are disposed when the RocksDB instance is disposed.
    
    参数:
    
    options - DBOptions instance.
    
    path - the path to the rocksdb.
    
    columnFamilyDescriptors - list of column family descriptors
    
    columnFamilyHandles - will be filled with ColumnFamilyHandle instances on open.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    DBOptions.setCreateIfMissing(boolean)
  - openReadOnly
```
public static RocksDB openReadOnly(java.lang.String path)
                            throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the default options.
    
    参数:
    
    path - the path to the RocksDB.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openReadOnly
```
public static RocksDB openReadOnly(Options options,
                                   java.lang.String path)
                            throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly, then this options instance will be GC'd automatically.
    
    参数:
    
    options - Options instance.
    
    path - the path to the RocksDB.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openReadOnly
```
public static RocksDB openReadOnly(Options options,
                                   java.lang.String path,
                                   boolean errorIfWalFileExists)
                            throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly, then this options instance will be GC'd automatically.
    
    参数:
    
    options - Options instance.
    
    path - the path to the RocksDB.
    
    errorIfWalFileExists - true to raise an error when opening the db if a Write Ahead Log file exists, false otherwise.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openReadOnly
```
public static RocksDB openReadOnly(java.lang.String path,
                                   java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                                   java.util.List<ColumnFamilyHandle> columnFamilyHandles)
                            throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the default options.
    
    参数:
    
    path - the path to the RocksDB.
    
    columnFamilyDescriptors - list of column family descriptors
    
    columnFamilyHandles - will be filled with ColumnFamilyHandle instances on open.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openReadOnly
```
public static RocksDB openReadOnly(DBOptions options,
                                   java.lang.String path,
                                   java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                                   java.util.List<ColumnFamilyHandle> columnFamilyHandles)
                            throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
    This open method allows to open RocksDB using a subset of available column families
    
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly,then this options instance will be GC'd automatically.
    
    参数:
    
    options - DBOptions instance.
    
    path - the path to the RocksDB.
    
    columnFamilyDescriptors - list of column family descriptors
    
    columnFamilyHandles - will be filled with ColumnFamilyHandle instances on open.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openReadOnly
```
public static RocksDB openReadOnly(DBOptions options,
                                   java.lang.String path,
                                   java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                                   java.util.List<ColumnFamilyHandle> columnFamilyHandles,
                                   boolean errorIfWalFileExists)
                            throws RocksDBException
```
    The factory constructor of RocksDB that opens a RocksDB instance in Read-Only mode given the path to the database using the specified options and db path.
    This open method allows to open RocksDB using a subset of available column families
    
    Options instance *should* not be disposed before all DBs using this options instance have been closed. If user doesn't call options dispose explicitly,then this options instance will be GC'd automatically.
    
    参数:
    
    options - DBOptions instance.
    
    path - the path to the RocksDB.
    
    columnFamilyDescriptors - list of column family descriptors
    
    columnFamilyHandles - will be filled with ColumnFamilyHandle instances on open.
    
    errorIfWalFileExists - true to raise an error when opening the db if a Write Ahead Log file exists, false otherwise.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openAsSecondary
```
public static RocksDB openAsSecondary(Options options,
                                      java.lang.String path,
                                      java.lang.String secondaryPath)
                               throws RocksDBException
```
    Open DB as secondary instance with only the default column family.
    The secondary instance can dynamically tail the MANIFEST of a primary that must have already been created. User can call tryCatchUpWithPrimary() to make the secondary instance catch up with primary (WAL tailing is NOT supported now) whenever the user feels necessary. Column families created by the primary after the secondary instance starts are currently ignored by the secondary instance. Column families opened by secondary and dropped by the primary will be dropped by secondary as well. However the user of the secondary instance can still access the data of such dropped column family as long as they do not destroy the corresponding column family handle. WAL tailing is not supported at present, but will arrive soon.
    
    参数:
    
    options - the options to open the secondary instance.
    
    path - the path to the primary RocksDB instance.
    
    secondaryPath - points to a directory where the secondary instance stores its info log
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - openAsSecondary
```
public static RocksDB openAsSecondary(DBOptions options,
                                      java.lang.String path,
                                      java.lang.String secondaryPath,
                                      java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors,
                                      java.util.List<ColumnFamilyHandle> columnFamilyHandles)
                               throws RocksDBException
```
    Open DB as secondary instance with column families. You can open a subset of column families in secondary mode.
    The secondary instance can dynamically tail the MANIFEST of a primary that must have already been created. User can call tryCatchUpWithPrimary() to make the secondary instance catch up with primary (WAL tailing is NOT supported now) whenever the user feels necessary. Column families created by the primary after the secondary instance starts are currently ignored by the secondary instance. Column families opened by secondary and dropped by the primary will be dropped by secondary as well. However the user of the secondary instance can still access the data of such dropped column family as long as they do not destroy the corresponding column family handle. WAL tailing is not supported at present, but will arrive soon.
    
    参数:
    
    options - the options to open the secondary instance.
    
    path - the path to the primary RocksDB instance.
    
    secondaryPath - points to a directory where the secondary instance stores its info log.
    
    columnFamilyDescriptors - list of column family descriptors
    
    columnFamilyHandles - will be filled with ColumnFamilyHandle instances on open.
    
    返回:
    
    a RocksDB instance on success, null if the specified RocksDB can not be opened.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - closeE
```
public void closeE()
            throws RocksDBException
```
    This is similar to close() except that it throws an exception if any error occurs.
    This will not fsync the WAL files. If syncing is required, the caller must first call syncWal() or write(WriteOptions, WriteBatch) using an empty write batch with WriteOptions.setSync(boolean) set to true.
    See also close().
    
    抛出:
    
    RocksDBException - if an error occurs whilst closing.
  - close
```
public void close()
```
    This is similar to closeE() except that it silently ignores any errors.
    This will not fsync the WAL files. If syncing is required, the caller must first call syncWal() or write(WriteOptions, WriteBatch) using an empty write batch with WriteOptions.setSync(boolean) set to true.
    See also close().
    
    指定者:
    
    close 在接口中 java.lang.AutoCloseable
    
    覆盖:
    
    close 在类中 AbstractImmutableNativeReference
  - listColumnFamilies
```
public static java.util.List<byte[]> listColumnFamilies(Options options,
                                                        java.lang.String path)
                                                 throws RocksDBException
```
    Static method to determine all available column families for a rocksdb database identified by path
    
    参数:
    
    options - Options for opening the database
    
    path - Absolute path to rocksdb database
    
    返回:
    
    List<byte[]> List containing the column family names
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - createColumnFamily
```
public ColumnFamilyHandle createColumnFamily(ColumnFamilyDescriptor columnFamilyDescriptor)
                                      throws RocksDBException
```
    Creates a new column family with the name columnFamilyName and allocates a ColumnFamilyHandle within an internal structure. The ColumnFamilyHandle is automatically disposed with DB disposal.
    
    参数:
    
    columnFamilyDescriptor - column family to be created.
    
    返回:
    
    ColumnFamilyHandle instance.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - createColumnFamilies
```
public java.util.List<ColumnFamilyHandle> createColumnFamilies(ColumnFamilyOptions columnFamilyOptions,
                                                               java.util.List<byte[]> columnFamilyNames)
                                                        throws RocksDBException
```
    Bulk create column families with the same column family options.
    
    参数:
    
    columnFamilyOptions - the options for the column families.
    
    columnFamilyNames - the names of the column families.
    
    返回:
    
    the handles to the newly created column families.
    
    抛出:
    
    RocksDBException - if an error occurs whilst creating the column families
  - createColumnFamilies
```
public java.util.List<ColumnFamilyHandle> createColumnFamilies(java.util.List<ColumnFamilyDescriptor> columnFamilyDescriptors)
                                                        throws RocksDBException
```
    Bulk create column families with the same column family options.
    
    参数:
    
    columnFamilyDescriptors - the descriptions of the column families.
    
    返回:
    
    the handles to the newly created column families.
    
    抛出:
    
    RocksDBException - if an error occurs whilst creating the column families
  - dropColumnFamily
```
public void dropColumnFamily(ColumnFamilyHandle columnFamilyHandle)
                      throws RocksDBException
```
    Drops the column family specified by columnFamilyHandle. This call only records a drop record in the manifest and prevents the column family from flushing and compacting.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - dropColumnFamilies
```
public void dropColumnFamilies(java.util.List<ColumnFamilyHandle> columnFamilies)
                        throws RocksDBException
```
    抛出:
    
    RocksDBException
  - destroyColumnFamilyHandle
```
public void destroyColumnFamilyHandle(ColumnFamilyHandle columnFamilyHandle)
```
    Deletes native column family handle of given ColumnFamilyHandle Java object and removes reference from ownedColumnFamilyHandles.
    
    参数:
    
    columnFamilyHandle - column family handle object.
  - put
```
public void put(byte[] key,
                byte[] value)
         throws RocksDBException
```
    Set the database entry for "key" to "value".
    
    参数:
    
    key - the specified key to be inserted.
    
    value - the value associated with the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - put
```
public void put(byte[] key,
                int offset,
                int len,
                byte[] value,
                int vOffset,
                int vLen)
         throws RocksDBException
```
    Set the database entry for "key" to "value".
    
    参数:
    
    key - The specified key to be inserted
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value associated with the specified key
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if errors happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - put
```
public void put(ColumnFamilyHandle columnFamilyHandle,
                byte[] key,
                byte[] value)
         throws RocksDBException
```
    Set the database entry for "key" to "value" in the specified column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the specified key to be inserted.
    
    value - the value associated with the specified key.
    throws IllegalArgumentException if column family is not present
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - put
```
public void put(ColumnFamilyHandle columnFamilyHandle,
                byte[] key,
                int offset,
                int len,
                byte[] value,
                int vOffset,
                int vLen)
         throws RocksDBException
```
    Set the database entry for "key" to "value" in the specified column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - The specified key to be inserted
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value associated with the specified key
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if errors happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - put
```
public void put(WriteOptions writeOpts,
                byte[] key,
                byte[] value)
         throws RocksDBException
```
    Set the database entry for "key" to "value".
    
    参数:
    
    writeOpts - WriteOptions instance.
    
    key - the specified key to be inserted.
    
    value - the value associated with the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - put
```
public void put(WriteOptions writeOpts,
                byte[] key,
                int offset,
                int len,
                byte[] value,
                int vOffset,
                int vLen)
         throws RocksDBException
```
    Set the database entry for "key" to "value".
    
    参数:
    
    writeOpts - WriteOptions instance.
    
    key - The specified key to be inserted
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value associated with the specified key
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - put
```
public void put(ColumnFamilyHandle columnFamilyHandle,
                WriteOptions writeOpts,
                byte[] key,
                byte[] value)
         throws RocksDBException
```
    Set the database entry for "key" to "value" for the specified column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpts - WriteOptions instance.
    
    key - the specified key to be inserted.
    
    value - the value associated with the specified key.
    throws IllegalArgumentException if column family is not present
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    IllegalArgumentException
  - put
```
public void put(ColumnFamilyHandle columnFamilyHandle,
                WriteOptions writeOpts,
                java.nio.ByteBuffer key,
                java.nio.ByteBuffer value)
         throws RocksDBException
```
    Set the database entry for "key" to "value" for the specified column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpts - WriteOptions instance.
    
    key - the specified key to be inserted. Position and limit is used. Supports direct buffer only.
    
    value - the value associated with the specified key. Position and limit is used. Supports direct buffer only.
    throws IllegalArgumentException if column family is not present
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    IllegalArgumentException
  - put
```
public void put(WriteOptions writeOpts,
                java.nio.ByteBuffer key,
                java.nio.ByteBuffer value)
         throws RocksDBException
```
    Set the database entry for "key" to "value".
    
    参数:
    
    writeOpts - WriteOptions instance.
    
    key - the specified key to be inserted. Position and limit is used. Supports direct buffer only.
    
    value - the value associated with the specified key. Position and limit is used. Supports direct buffer only.
    throws IllegalArgumentException if column family is not present
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    另请参阅:
    
    IllegalArgumentException
  - put
```
public void put(ColumnFamilyHandle columnFamilyHandle,
                WriteOptions writeOpts,
                byte[] key,
                int offset,
                int len,
                byte[] value,
                int vOffset,
                int vLen)
         throws RocksDBException
```
    Set the database entry for "key" to "value" for the specified column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpts - WriteOptions instance.
    
    key - The specified key to be inserted
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value associated with the specified key
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - delete
```
public void delete(byte[] key)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(byte[] key,
                   int offset,
                   int len)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    key - Key to delete within database
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(ColumnFamilyHandle columnFamilyHandle,
                   byte[] key)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(ColumnFamilyHandle columnFamilyHandle,
                   byte[] key,
                   int offset,
                   int len)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - Key to delete within database
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(WriteOptions writeOpt,
                   byte[] key)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    writeOpt - WriteOptions to be used with delete operation
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(WriteOptions writeOpt,
                   byte[] key,
                   int offset,
                   int len)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    writeOpt - WriteOptions to be used with delete operation
    
    key - Key to delete within database
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(ColumnFamilyHandle columnFamilyHandle,
                   WriteOptions writeOpt,
                   byte[] key)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpt - WriteOptions to be used with delete operation
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(ColumnFamilyHandle columnFamilyHandle,
                   WriteOptions writeOpt,
                   byte[] key,
                   int offset,
                   int len)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpt - WriteOptions to be used with delete operation
    
    key - Key to delete within database
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(ReadOptions opt,
               java.nio.ByteBuffer key,
               java.nio.ByteBuffer value)
        throws RocksDBException
```
    Get the value associated with the specified key within column family.
    
    参数:
    
    opt - ReadOptions instance.
    
    key - the key to retrieve the value. It is using position and limit. Supports direct buffer only.
    
    value - the out-value to receive the retrieved value. It is using position and limit. Limit is set according to value size. Supports direct buffer only.
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(ColumnFamilyHandle columnFamilyHandle,
               ReadOptions opt,
               java.nio.ByteBuffer key,
               java.nio.ByteBuffer value)
        throws RocksDBException
```
    Get the value associated with the specified key within column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    opt - ReadOptions instance.
    
    key - the key to retrieve the value. It is using position and limit. Supports direct buffer only.
    
    value - the out-value to receive the retrieved value. It is using position and limit. Limit is set according to value size. Supports direct buffer only.
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - singleDelete
```
@Experimental(value="Performance optimization for a very specific workload")
public void singleDelete(byte[] key)
                                                                                               throws RocksDBException
```
    Remove the database entry for key. Requires that the key exists and was not overwritten. It is not an error if the key did not exist in the database.
    If a key is overwritten (by calling put(byte[], byte[]) multiple times), then the result of calling SingleDelete() on this key is undefined. SingleDelete() only behaves correctly if there has been only one Put() for this key since the previous call to SingleDelete() for this key.
    This feature is currently an experimental performance optimization for a very specific workload. It is up to the caller to ensure that SingleDelete is only used for a key that is not deleted using Delete() or written using Merge(). Mixing SingleDelete operations with Deletes and Merges can result in undefined behavior.
    
    参数:
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - singleDelete
```
@Experimental(value="Performance optimization for a very specific workload")
public void singleDelete(ColumnFamilyHandle columnFamilyHandle,
                                                                                                      byte[] key)
                                                                                               throws RocksDBException
```
    Remove the database entry for key. Requires that the key exists and was not overwritten. It is not an error if the key did not exist in the database.
    If a key is overwritten (by calling put(byte[], byte[]) multiple times), then the result of calling SingleDelete() on this key is undefined. SingleDelete() only behaves correctly if there has been only one Put() for this key since the previous call to SingleDelete() for this key.
    This feature is currently an experimental performance optimization for a very specific workload. It is up to the caller to ensure that SingleDelete is only used for a key that is not deleted using Delete() or written using Merge(). Mixing SingleDelete operations with Deletes and Merges can result in undefined behavior.
    
    参数:
    
    columnFamilyHandle - The column family to delete the key from
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - singleDelete
```
@Experimental(value="Performance optimization for a very specific workload")
public void singleDelete(WriteOptions writeOpt,
                                                                                                      byte[] key)
                                                                                               throws RocksDBException
```
    Remove the database entry for key. Requires that the key exists and was not overwritten. It is not an error if the key did not exist in the database.
    If a key is overwritten (by calling put(byte[], byte[]) multiple times), then the result of calling SingleDelete() on this key is undefined. SingleDelete() only behaves correctly if there has been only one Put() for this key since the previous call to SingleDelete() for this key.
    This feature is currently an experimental performance optimization for a very specific workload. It is up to the caller to ensure that SingleDelete is only used for a key that is not deleted using Delete() or written using Merge(). Mixing SingleDelete operations with Deletes and Merges can result in undefined behavior.
    Note: consider setting WriteOptions.setSync(boolean) true.
    
    参数:
    
    writeOpt - Write options for the delete
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - singleDelete
```
@Experimental(value="Performance optimization for a very specific workload")
public void singleDelete(ColumnFamilyHandle columnFamilyHandle,
                                                                                                      WriteOptions writeOpt,
                                                                                                      byte[] key)
                                                                                               throws RocksDBException
```
    Remove the database entry for key. Requires that the key exists and was not overwritten. It is not an error if the key did not exist in the database.
    If a key is overwritten (by calling put(byte[], byte[]) multiple times), then the result of calling SingleDelete() on this key is undefined. SingleDelete() only behaves correctly if there has been only one Put() for this key since the previous call to SingleDelete() for this key.
    This feature is currently an experimental performance optimization for a very specific workload. It is up to the caller to ensure that SingleDelete is only used for a key that is not deleted using Delete() or written using Merge(). Mixing SingleDelete operations with Deletes and Merges can result in undefined behavior.
    Note: consider setting WriteOptions.setSync(boolean) true.
    
    参数:
    
    columnFamilyHandle - The column family to delete the key from
    
    writeOpt - Write options for the delete
    
    key - Key to delete within database
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - deleteRange
```
public void deleteRange(byte[] beginKey,
                        byte[] endKey)
                 throws RocksDBException
```
    Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error. It is not an error if no keys exist in the range ["beginKey", "endKey").
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    beginKey - First key to delete within database (inclusive)
    
    endKey - Last key to delete within database (exclusive)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - deleteRange
```
public void deleteRange(ColumnFamilyHandle columnFamilyHandle,
                        byte[] beginKey,
                        byte[] endKey)
                 throws RocksDBException
```
    Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error. It is not an error if no keys exist in the range ["beginKey", "endKey").
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    beginKey - First key to delete within database (inclusive)
    
    endKey - Last key to delete within database (exclusive)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - deleteRange
```
public void deleteRange(WriteOptions writeOpt,
                        byte[] beginKey,
                        byte[] endKey)
                 throws RocksDBException
```
    Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error. It is not an error if no keys exist in the range ["beginKey", "endKey").
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    writeOpt - WriteOptions to be used with delete operation
    
    beginKey - First key to delete within database (inclusive)
    
    endKey - Last key to delete within database (exclusive)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - deleteRange
```
public void deleteRange(ColumnFamilyHandle columnFamilyHandle,
                        WriteOptions writeOpt,
                        byte[] beginKey,
                        byte[] endKey)
                 throws RocksDBException
```
    Removes the database entries in the range ["beginKey", "endKey"), i.e., including "beginKey" and excluding "endKey". a non-OK status on error. It is not an error if no keys exist in the range ["beginKey", "endKey").
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpt - WriteOptions to be used with delete operation
    
    beginKey - First key to delete within database (included)
    
    endKey - Last key to delete within database (excluded)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - merge
```
public void merge(byte[] key,
                  byte[] value)
           throws RocksDBException
```
    Add merge operand for key/value pair.
    
    参数:
    
    key - the specified key to be merged.
    
    value - the value to be merged with the current value for the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - merge
```
public void merge(byte[] key,
                  int offset,
                  int len,
                  byte[] value,
                  int vOffset,
                  int vLen)
           throws RocksDBException
```
    Add merge operand for key/value pair.
    
    参数:
    
    key - the specified key to be merged.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value to be merged with the current value for the specified key.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - merge
```
public void merge(ColumnFamilyHandle columnFamilyHandle,
                  byte[] key,
                  byte[] value)
           throws RocksDBException
```
    Add merge operand for key/value pair in a ColumnFamily.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the specified key to be merged.
    
    value - the value to be merged with the current value for the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - merge
```
public void merge(ColumnFamilyHandle columnFamilyHandle,
                  byte[] key,
                  int offset,
                  int len,
                  byte[] value,
                  int vOffset,
                  int vLen)
           throws RocksDBException
```
    Add merge operand for key/value pair in a ColumnFamily.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the specified key to be merged.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value to be merged with the current value for the specified key.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - merge
```
public void merge(WriteOptions writeOpts,
                  byte[] key,
                  byte[] value)
           throws RocksDBException
```
    Add merge operand for key/value pair.
    
    参数:
    
    writeOpts - WriteOptions for this write.
    
    key - the specified key to be merged.
    
    value - the value to be merged with the current value for the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - merge
```
public void merge(WriteOptions writeOpts,
                  byte[] key,
                  int offset,
                  int len,
                  byte[] value,
                  int vOffset,
                  int vLen)
           throws RocksDBException
```
    Add merge operand for key/value pair.
    
    参数:
    
    writeOpts - WriteOptions for this write.
    
    key - the specified key to be merged.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    value - the value to be merged with the current value for the specified key.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - delete
```
public void delete(WriteOptions writeOpt,
                   java.nio.ByteBuffer key)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    writeOpt - WriteOptions to be used with delete operation
    
    key - Key to delete within database. It is using position and limit. Supports direct buffer only.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - delete
```
public void delete(ColumnFamilyHandle columnFamilyHandle,
                   WriteOptions writeOpt,
                   java.nio.ByteBuffer key)
            throws RocksDBException
```
    Delete the database entry (if any) for "key". Returns OK on success, and a non-OK status on error. It is not an error if "key" did not exist in the database.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpt - WriteOptions to be used with delete operation
    
    key - Key to delete within database. It is using position and limit. Supports direct buffer only.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - merge
```
public void merge(ColumnFamilyHandle columnFamilyHandle,
                  WriteOptions writeOpts,
                  byte[] key,
                  byte[] value)
           throws RocksDBException
```
    Add merge operand for key/value pair.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpts - WriteOptions for this write.
    
    key - the specified key to be merged.
    
    value - the value to be merged with the current value for the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - merge
```
public void merge(ColumnFamilyHandle columnFamilyHandle,
                  WriteOptions writeOpts,
                  byte[] key,
                  int offset,
                  int len,
                  byte[] value,
                  int vOffset,
                  int vLen)
           throws RocksDBException
```
    Add merge operand for key/value pair.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    writeOpts - WriteOptions for this write.
    
    key - the specified key to be merged.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the value to be merged with the current value for the specified key.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IndexOutOfBoundsException - if an offset or length is out of bounds
  - write
```
public void write(WriteOptions writeOpts,
                  WriteBatch updates)
           throws RocksDBException
```
    Apply the specified updates to the database.
    
    参数:
    
    writeOpts - WriteOptions instance
    
    updates - WriteBatch instance
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - write
```
public void write(WriteOptions writeOpts,
                  WriteBatchWithIndex updates)
           throws RocksDBException
```
    Apply the specified updates to the database.
    
    参数:
    
    writeOpts - WriteOptions instance
    
    updates - WriteBatchWithIndex instance
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(byte[] key,
               byte[] value)
        throws RocksDBException
```
    Get the value associated with the specified key within column family*
    
    参数:
    
    key - the key to retrieve the value.
    
    value - the out-value to receive the retrieved value.
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(byte[] key,
               int offset,
               int len,
               byte[] value,
               int vOffset,
               int vLen)
        throws RocksDBException
```
    Get the value associated with the specified key within column family*
    
    参数:
    
    key - the key to retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the out-value to receive the retrieved value.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "value".length
    
    vLen - the length of the "value" array to be used, must be non-negative and and no larger than ("value".length - offset)
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(ColumnFamilyHandle columnFamilyHandle,
               byte[] key,
               byte[] value)
        throws RocksDBException,
               java.lang.IllegalArgumentException
```
    Get the value associated with the specified key within column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the key to retrieve the value.
    
    value - the out-value to receive the retrieved value.
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IllegalArgumentException
  - get
```
public int get(ColumnFamilyHandle columnFamilyHandle,
               byte[] key,
               int offset,
               int len,
               byte[] value,
               int vOffset,
               int vLen)
        throws RocksDBException,
               java.lang.IllegalArgumentException
```
    Get the value associated with the specified key within column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the key to retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative an no larger than ("key".length - offset)
    
    value - the out-value to receive the retrieved value.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IllegalArgumentException
  - get
```
public int get(ReadOptions opt,
               byte[] key,
               byte[] value)
        throws RocksDBException
```
    Get the value associated with the specified key.
    
    参数:
    
    opt - ReadOptions instance.
    
    key - the key to retrieve the value.
    
    value - the out-value to receive the retrieved value.
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(ReadOptions opt,
               byte[] key,
               int offset,
               int len,
               byte[] value,
               int vOffset,
               int vLen)
        throws RocksDBException
```
    Get the value associated with the specified key.
    
    参数:
    
    opt - ReadOptions instance.
    
    key - the key to retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    value - the out-value to receive the retrieved value.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, must be non-negative and no larger than ("value".length - offset)
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(ColumnFamilyHandle columnFamilyHandle,
               ReadOptions opt,
               byte[] key,
               byte[] value)
        throws RocksDBException
```
    Get the value associated with the specified key within column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    opt - ReadOptions instance.
    
    key - the key to retrieve the value.
    
    value - the out-value to receive the retrieved value.
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public int get(ColumnFamilyHandle columnFamilyHandle,
               ReadOptions opt,
               byte[] key,
               int offset,
               int len,
               byte[] value,
               int vOffset,
               int vLen)
        throws RocksDBException
```
    Get the value associated with the specified key within column family.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    opt - ReadOptions instance.
    
    key - the key to retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and and no larger than ("key".length - offset)
    
    value - the out-value to receive the retrieved value.
    
    vOffset - the offset of the "value" array to be used, must be non-negative and no longer than "key".length
    
    vLen - the length of the "value" array to be used, and must be non-negative and no larger than ("value".length - offset)
    
    返回:
    
    The size of the actual value that matches the specified key in byte. If the return value is greater than the length of value, then it indicates that the size of the input buffer value is insufficient and partial result will be returned. RocksDB.NOT_FOUND will be returned if the value not found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(byte[] key)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    key - the key retrieve the value.
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(byte[] key,
                  int offset,
                  int len)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    key - the key retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(ColumnFamilyHandle columnFamilyHandle,
                  byte[] key)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the key retrieve the value.
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(ColumnFamilyHandle columnFamilyHandle,
                  byte[] key,
                  int offset,
                  int len)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the key retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(ReadOptions opt,
                  byte[] key)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    key - the key retrieve the value.
    
    opt - Read options.
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(ReadOptions opt,
                  byte[] key,
                  int offset,
                  int len)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    key - the key retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    opt - Read options.
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(ColumnFamilyHandle columnFamilyHandle,
                  ReadOptions opt,
                  byte[] key)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the key retrieve the value.
    
    opt - Read options.
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - get
```
public byte[] get(ColumnFamilyHandle columnFamilyHandle,
                  ReadOptions opt,
                  byte[] key,
                  int offset,
                  int len)
           throws RocksDBException
```
    The simplified version of get which returns a new byte array storing the value associated with the specified input key if any. null will be returned if the specified key is not found.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - the key retrieve the value.
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than ("key".length - offset)
    
    opt - Read options.
    
    返回:
    
    a byte array storing the value associated with the input key if any. null if it does not find the specified key.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - multiGetAsList
```
public java.util.List<byte[]> multiGetAsList(java.util.List<byte[]> keys)
                                      throws RocksDBException
```
    Takes a list of keys, and returns a list of values for the given list of keys. List will contain null for keys which could not be found.
    
    参数:
    
    keys - List of keys for which values need to be retrieved.
    
    返回:
    
    List of values for the given list of keys. List will contain null for keys which could not be found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - multiGetAsList
```
public java.util.List<byte[]> multiGetAsList(java.util.List<ColumnFamilyHandle> columnFamilyHandleList,
                                             java.util.List<byte[]> keys)
                                      throws RocksDBException,
                                             java.lang.IllegalArgumentException
```
    Returns a list of values for the given list of keys. List will contain null for keys which could not be found.
    Note: Every key needs to have a related column family name in columnFamilyHandleList.
    
    参数:
    
    columnFamilyHandleList - List containing ColumnFamilyHandle instances.
    
    keys - List of keys for which values need to be retrieved.
    
    返回:
    
    List of values for the given list of keys. List will contain null for keys which could not be found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IllegalArgumentException - thrown if the size of passed keys is not equal to the amount of passed column family handles.
  - multiGetAsList
```
public java.util.List<byte[]> multiGetAsList(ReadOptions opt,
                                             java.util.List<byte[]> keys)
                                      throws RocksDBException
```
    Returns a list of values for the given list of keys. List will contain null for keys which could not be found.
    
    参数:
    
    opt - Read options.
    
    keys - of keys for which values need to be retrieved.
    
    返回:
    
    List of values for the given list of keys. List will contain null for keys which could not be found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - multiGetAsList
```
public java.util.List<byte[]> multiGetAsList(ReadOptions opt,
                                             java.util.List<ColumnFamilyHandle> columnFamilyHandleList,
                                             java.util.List<byte[]> keys)
                                      throws RocksDBException
```
    Returns a list of values for the given list of keys. List will contain null for keys which could not be found.
    Note: Every key needs to have a related column family name in columnFamilyHandleList.
    
    参数:
    
    opt - Read options.
    
    columnFamilyHandleList - List containing ColumnFamilyHandle instances.
    
    keys - of keys for which values need to be retrieved.
    
    返回:
    
    List of values for the given list of keys. List will contain null for keys which could not be found.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
    
    java.lang.IllegalArgumentException - thrown if the size of passed keys is not equal to the amount of passed column family handles.
  - multiGetByteBuffers
```
public java.util.List<ByteBufferGetStatus> multiGetByteBuffers(java.util.List<java.nio.ByteBuffer> keys,
                                                               java.util.List<java.nio.ByteBuffer> values)
                                                        throws RocksDBException
```
    Fetches a list of values for the given list of keys, all from the default column family.
    
    参数:
    
    keys - list of keys for which values need to be retrieved.
    
    values - list of buffers to return retrieved values in
    
    返回:
    
    list of number of bytes in DB for each requested key this can be more than the size of the corresponding buffer; then the buffer will be filled with the appropriate truncation of the database value.
    
    抛出:
    
    RocksDBException - if error happens in underlying native library.
    
    java.lang.IllegalArgumentException - thrown if the number of passed keys and passed values do not match.
  - multiGetByteBuffers
```
public java.util.List<ByteBufferGetStatus> multiGetByteBuffers(ReadOptions readOptions,
                                                               java.util.List<java.nio.ByteBuffer> keys,
                                                               java.util.List<java.nio.ByteBuffer> values)
                                                        throws RocksDBException
```
    Fetches a list of values for the given list of keys, all from the default column family.
    
    参数:
    
    readOptions - Read options
    
    keys - list of keys for which values need to be retrieved.
    
    values - list of buffers to return retrieved values in
    
    返回:
    
    the list of values for the given list of keys
    
    抛出:
    
    RocksDBException - if error happens in underlying native library.
    
    java.lang.IllegalArgumentException - thrown if the number of passed keys and passed values do not match.
  - multiGetByteBuffers
```
public java.util.List<ByteBufferGetStatus> multiGetByteBuffers(java.util.List<ColumnFamilyHandle> columnFamilyHandleList,
                                                               java.util.List<java.nio.ByteBuffer> keys,
                                                               java.util.List<java.nio.ByteBuffer> values)
                                                        throws RocksDBException
```
    Fetches a list of values for the given list of keys.
    Note: Every key needs to have a related column family name in columnFamilyHandleList.
    
    参数:
    
    columnFamilyHandleList - List containing ColumnFamilyHandle instances.
    
    keys - list of keys for which values need to be retrieved.
    
    values - list of buffers to return retrieved values in
    
    返回:
    
    the list of values for the given list of keys
    
    抛出:
    
    RocksDBException - if error happens in underlying native library.
    
    java.lang.IllegalArgumentException - thrown if the number of passed keys, passed values and passed column family handles do not match.
  - multiGetByteBuffers
```
public java.util.List<ByteBufferGetStatus> multiGetByteBuffers(ReadOptions readOptions,
                                                               java.util.List<ColumnFamilyHandle> columnFamilyHandleList,
                                                               java.util.List<java.nio.ByteBuffer> keys,
                                                               java.util.List<java.nio.ByteBuffer> values)
                                                        throws RocksDBException
```
    Fetches a list of values for the given list of keys.
    Note: Every key needs to have a related column family name in columnFamilyHandleList.
    
    参数:
    
    readOptions - Read options
    
    columnFamilyHandleList - List containing ColumnFamilyHandle instances.
    
    keys - list of keys for which values need to be retrieved.
    
    values - list of buffers to return retrieved values in
    
    返回:
    
    the list of values for the given list of keys
    
    抛出:
    
    RocksDBException - if error happens in underlying native library.
    
    java.lang.IllegalArgumentException - thrown if the number of passed keys, passed values and passed column family handles do not match.
  - keyMayExist
```
public boolean keyMayExist(byte[] key,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(byte[]). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    key - byte array of a key to search for
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(byte[] key,
                           int offset,
                           int len,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(byte[], int, int). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    key - byte array of a key to search for
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than "key".length
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                           byte[] key,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(ColumnFamilyHandle,byte[]). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - byte array of a key to search for
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                           byte[] key,
                           int offset,
                           int len,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(ColumnFamilyHandle, byte[], int, int). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    key - byte array of a key to search for
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than "key".length
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ReadOptions readOptions,
                           byte[] key,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a true negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(ReadOptions, byte[]). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    readOptions - ReadOptions instance
    
    key - byte array of a key to search for
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ReadOptions readOptions,
                           byte[] key,
                           int offset,
                           int len,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a true negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(ReadOptions, byte[], int, int). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    readOptions - ReadOptions instance
    
    key - byte array of a key to search for
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than "key".length
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                           ReadOptions readOptions,
                           byte[] key,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a true negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(ColumnFamilyHandle, ReadOptions, byte[]). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    readOptions - ReadOptions instance
    
    key - byte array of a key to search for
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                           ReadOptions readOptions,
                           byte[] key,
                           int offset,
                           int len,
                           Holder<byte[]> valueHolder)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    If the caller wants to obtain value when the key is found in memory, then valueHolder must be set.
    This check is potentially lighter-weight than invoking get(ColumnFamilyHandle, ReadOptions, byte[], int, int). One way to make this lighter weight is to avoid doing any IOs.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    readOptions - ReadOptions instance
    
    key - byte array of a key to search for
    
    offset - the offset of the "key" array to be used, must be non-negative and no larger than "key".length
    
    len - the length of the "key" array to be used, must be non-negative and no larger than "key".length
    
    valueHolder - non-null to retrieve the value if it is found, or null if the value is not needed. If non-null, upon return of the function, the value will be set if it could be retrieved.
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(java.nio.ByteBuffer key)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    
    参数:
    
    key - bytebuffer containing the value of the key
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                           java.nio.ByteBuffer key)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    
    参数:
    
    columnFamilyHandle - the ColumnFamilyHandle to look for the key in
    
    key - bytebuffer containing the value of the key
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public boolean keyMayExist(ReadOptions readOptions,
                           java.nio.ByteBuffer key)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    
    参数:
    
    readOptions - the ReadOptions to use when reading the key/value
    
    key - bytebuffer containing the value of the key
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public KeyMayExist keyMayExist(java.nio.ByteBuffer key,
                               java.nio.ByteBuffer value)
```
    If the key definitely does not exist in the database, then this method returns KeyMayExist.KeyMayExistEnum.kNotExist, otherwise if it can with best effort retreive the value, it returns KeyMayExist.KeyMayExistEnum.kExistsWithValue otherwise it returns KeyMayExist.KeyMayExistEnum.kExistsWithoutValue. The choice not to return a value which might exist is at the discretion of the implementation; the only guarantee is that KeyMayExist.KeyMayExistEnum.kNotExist is an assurance that the key does not exist.
    
    参数:
    
    key - bytebuffer containing the value of the key
    
    value - bytebuffer which will receive a value if the key exists and a value is known
    
    返回:
    
    a KeyMayExist object reporting if key may exist and if a value is provided
  - keyMayExist
```
public KeyMayExist keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                               java.nio.ByteBuffer key,
                               java.nio.ByteBuffer value)
```
    If the key definitely does not exist in the database, then this method returns KeyMayExist.KeyMayExistEnum.kNotExist, otherwise if it can with best effort retreive the value, it returns KeyMayExist.KeyMayExistEnum.kExistsWithValue otherwise it returns KeyMayExist.KeyMayExistEnum.kExistsWithoutValue. The choice not to return a value which might exist is at the discretion of the implementation; the only guarantee is that KeyMayExist.KeyMayExistEnum.kNotExist is an assurance that the key does not exist.
    
    参数:
    
    columnFamilyHandle - the ColumnFamilyHandle to look for the key in
    
    key - bytebuffer containing the value of the key
    
    value - bytebuffer which will receive a value if the key exists and a value is known
    
    返回:
    
    a KeyMayExist object reporting if key may exist and if a value is provided
  - keyMayExist
```
public KeyMayExist keyMayExist(ReadOptions readOptions,
                               java.nio.ByteBuffer key,
                               java.nio.ByteBuffer value)
```
    If the key definitely does not exist in the database, then this method returns KeyMayExist.KeyMayExistEnum.kNotExist, otherwise if it can with best effort retreive the value, it returns KeyMayExist.KeyMayExistEnum.kExistsWithValue otherwise it returns KeyMayExist.KeyMayExistEnum.kExistsWithoutValue. The choice not to return a value which might exist is at the discretion of the implementation; the only guarantee is that KeyMayExist.KeyMayExistEnum.kNotExist is an assurance that the key does not exist.
    
    参数:
    
    readOptions - the ReadOptions to use when reading the key/value
    
    key - bytebuffer containing the value of the key
    
    value - bytebuffer which will receive a value if the key exists and a value is known
    
    返回:
    
    a KeyMayExist object reporting if key may exist and if a value is provided
  - keyMayExist
```
public boolean keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                           ReadOptions readOptions,
                           java.nio.ByteBuffer key)
```
    If the key definitely does not exist in the database, then this method returns false, otherwise it returns true if the key might exist. That is to say that this method is probabilistic and may return false positives, but never a false negative.
    
    参数:
    
    columnFamilyHandle - the ColumnFamilyHandle to look for the key in
    
    readOptions - the ReadOptions to use when reading the key/value
    
    key - bytebuffer containing the value of the key
    
    返回:
    
    false if the key definitely does not exist in the database, otherwise true.
  - keyMayExist
```
public KeyMayExist keyMayExist(ColumnFamilyHandle columnFamilyHandle,
                               ReadOptions readOptions,
                               java.nio.ByteBuffer key,
                               java.nio.ByteBuffer value)
```
    If the key definitely does not exist in the database, then this method returns KeyMayExist.KeyMayExistEnum.kNotExist, otherwise if it can with best effort retreive the value, it returns KeyMayExist.KeyMayExistEnum.kExistsWithValue otherwise it returns KeyMayExist.KeyMayExistEnum.kExistsWithoutValue. The choice not to return a value which might exist is at the discretion of the implementation; the only guarantee is that KeyMayExist.KeyMayExistEnum.kNotExist is an assurance that the key does not exist.
    
    参数:
    
    columnFamilyHandle - the ColumnFamilyHandle to look for the key in
    
    readOptions - the ReadOptions to use when reading the key/value
    
    key - bytebuffer containing the value of the key
    
    value - bytebuffer which will receive a value if the key exists and a value is known
    
    返回:
    
    a KeyMayExist object reporting if key may exist and if a value is provided
  - newIterator
```
public RocksIterator newIterator()
```
    Return a heap-allocated iterator over the contents of the database. The result of newIterator() is initially invalid (caller must call one of the Seek methods on the iterator before using it).
    
    Caller should close the iterator when it is no longer needed. The returned iterator should be closed before this db is closed.
    
    返回:
    
    instance of iterator object.
  - newIterator
```
public RocksIterator newIterator(ReadOptions readOptions)
```
    Return a heap-allocated iterator over the contents of the database. The result of newIterator() is initially invalid (caller must call one of the Seek methods on the iterator before using it).
    
    Caller should close the iterator when it is no longer needed. The returned iterator should be closed before this db is closed.
    
    参数:
    
    readOptions - ReadOptions instance.
    
    返回:
    
    instance of iterator object.
  - newIterator
```
public RocksIterator newIterator(ColumnFamilyHandle columnFamilyHandle)
```
    Return a heap-allocated iterator over the contents of a ColumnFamily. The result of newIterator() is initially invalid (caller must call one of the Seek methods on the iterator before using it).
    
    Caller should close the iterator when it is no longer needed. The returned iterator should be closed before this db is closed.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    返回:
    
    instance of iterator object.
  - newIterator
```
public RocksIterator newIterator(ColumnFamilyHandle columnFamilyHandle,
                                 ReadOptions readOptions)
```
    Return a heap-allocated iterator over the contents of a ColumnFamily. The result of newIterator() is initially invalid (caller must call one of the Seek methods on the iterator before using it).
    
    Caller should close the iterator when it is no longer needed. The returned iterator should be closed before this db is closed.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance
    
    readOptions - ReadOptions instance.
    
    返回:
    
    instance of iterator object.
  - newIterators
```
public java.util.List<RocksIterator> newIterators(java.util.List<ColumnFamilyHandle> columnFamilyHandleList)
                                           throws RocksDBException
```
    Returns iterators from a consistent database state across multiple column families. Iterators are heap allocated and need to be deleted before the db is deleted
    
    参数:
    
    columnFamilyHandleList - List containing ColumnFamilyHandle instances.
    
    返回:
    
    List containing RocksIterator instances
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - newIterators
```
public java.util.List<RocksIterator> newIterators(java.util.List<ColumnFamilyHandle> columnFamilyHandleList,
                                                  ReadOptions readOptions)
                                           throws RocksDBException
```
    Returns iterators from a consistent database state across multiple column families. Iterators are heap allocated and need to be deleted before the db is deleted
    
    参数:
    
    columnFamilyHandleList - List containing ColumnFamilyHandle instances.
    
    readOptions - ReadOptions instance.
    
    返回:
    
    List containing RocksIterator instances
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - getSnapshot
```
public Snapshot getSnapshot()
```
    Return a handle to the current DB state. Iterators created with this handle will all observe a stable snapshot of the current DB state. The caller must call ReleaseSnapshot(result) when the snapshot is no longer needed.
    
    nullptr will be returned if the DB fails to take a snapshot or does not support snapshot.
    
    返回:
    
    Snapshot Snapshot instance
  - releaseSnapshot
```
public void releaseSnapshot(Snapshot snapshot)
```
    Release a previously acquired snapshot.
    The caller must not use "snapshot" after this call.
    
    参数:
    
    snapshot - Snapshot instance
  - getProperty
```
public java.lang.String getProperty(ColumnFamilyHandle columnFamilyHandle,
                                    java.lang.String property)
                             throws RocksDBException
```
    DB implements can export properties about their state via this method on a per column family level.
    If property is a valid property understood by this DB implementation, fills value with its current value and returns true. Otherwise returns false.
    
    Valid property names include:
    - "rocksdb.num-files-at-level<N>" - return the number of files at level <N>, where <N> is an ASCII representation of a level number (e.g. "0").
    - "rocksdb.stats" - returns a multi-line string that describes statistics about the internal operation of the DB.
    - "rocksdb.sstables" - returns a multi-line string that describes all of the sstables that make up the db contents.
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family.
    
    property - to be fetched. See above for examples
    
    返回:
    
    property value
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - getProperty
```
public java.lang.String getProperty(java.lang.String property)
                             throws RocksDBException
```
    DB implementations can export properties about their state via this method. If "property" is a valid property understood by this DB implementation, fills "*value" with its current value and returns true. Otherwise returns false.
    Valid property names include:
    - "rocksdb.num-files-at-level<N>" - return the number of files at level <N>, where <N> is an ASCII representation of a level number (e.g. "0").
    - "rocksdb.stats" - returns a multi-line string that describes statistics about the internal operation of the DB.
    - "rocksdb.sstables" - returns a multi-line string that describes all of the sstables that make up the db contents.
    参数:
    
    property - to be fetched. See above for examples
    
    返回:
    
    property value
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - getMapProperty
```
public java.util.Map<java.lang.String,java.lang.String> getMapProperty(java.lang.String property)
                                                                throws RocksDBException
```
    Gets a property map.
    
    参数:
    
    property - to be fetched.
    
    返回:
    
    the property map
    
    抛出:
    
    RocksDBException - if an error happens in the underlying native code.
  - getMapProperty
```
public java.util.Map<java.lang.String,java.lang.String> getMapProperty(ColumnFamilyHandle columnFamilyHandle,
                                                                       java.lang.String property)
                                                                throws RocksDBException
```
    Gets a property map.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family.
    
    property - to be fetched.
    
    返回:
    
    the property map
    
    抛出:
    
    RocksDBException - if an error happens in the underlying native code.
  - getLongProperty
```
public long getLongProperty(java.lang.String property)
                     throws RocksDBException
```
    Similar to GetProperty(), but only works for a subset of properties whose return value is a numerical value. Return the value as long.
    
    Note: As the returned property is of type uint64_t on C++ side the returning value can be negative because Java supports in Java 7 only signed long values.
    
    Java 7: To mitigate the problem of the non existent unsigned long tpye, values should be encapsulated using BigInteger to reflect the correct value. The correct behavior is guaranteed if 2^64 is added to negative values.
    
    Java 8: In Java 8 the value should be treated as unsigned long using provided methods of type Long.
    
    参数:
    
    property - to be fetched.
    
    返回:
    
    numerical property value.
    
    抛出:
    
    RocksDBException - if an error happens in the underlying native code.
  - getLongProperty
```
public long getLongProperty(ColumnFamilyHandle columnFamilyHandle,
                            java.lang.String property)
                     throws RocksDBException
```
    Similar to GetProperty(), but only works for a subset of properties whose return value is a numerical value. Return the value as long.
    
    Note: As the returned property is of type uint64_t on C++ side the returning value can be negative because Java supports in Java 7 only signed long values.
    
    Java 7: To mitigate the problem of the non existent unsigned long tpye, values should be encapsulated using BigInteger to reflect the correct value. The correct behavior is guaranteed if 2^64 is added to negative values.
    
    Java 8: In Java 8 the value should be treated as unsigned long using provided methods of type Long.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family
    
    property - to be fetched.
    
    返回:
    
    numerical property value
    
    抛出:
    
    RocksDBException - if an error happens in the underlying native code.
  - resetStats
```
public void resetStats()
                throws RocksDBException
```
    Reset internal stats for DB and all column families.
    Note this doesn't reset Options.statistics() as it is not owned by DB.
    
    抛出:
    
    RocksDBException - if an error occurs whilst reseting the stats
  - getAggregatedLongProperty
```
public long getAggregatedLongProperty(java.lang.String property)
                               throws RocksDBException
```
    Return sum of the getLongProperty of all the column families
    
    Note: As the returned property is of type uint64_t on C++ side the returning value can be negative because Java supports in Java 7 only signed long values.
    
    Java 7: To mitigate the problem of the non existent unsigned long tpye, values should be encapsulated using BigInteger to reflect the correct value. The correct behavior is guaranteed if 2^64 is added to negative values.
    
    Java 8: In Java 8 the value should be treated as unsigned long using provided methods of type Long.
    
    参数:
    
    property - to be fetched.
    
    返回:
    
    numerical property value
    
    抛出:
    
    RocksDBException - if an error happens in the underlying native code.
  - getApproximateSizes
```
public long[] getApproximateSizes(ColumnFamilyHandle columnFamilyHandle,
                                  java.util.List<Range> ranges,
                                  SizeApproximationFlag... sizeApproximationFlags)
```
    Get the approximate file system space used by keys in each range.
    Note that the returned sizes measure file system space usage, so if the user data compresses by a factor of ten, the returned sizes will be one-tenth the size of the corresponding user data size.
    If sizeApproximationFlags defines whether the returned size should include the recently written data in the mem-tables (if the mem-table type supports it), data serialized to disk, or both.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family
    
    ranges - the ranges over which to approximate sizes
    
    sizeApproximationFlags - flags to determine what to include in the approximation.
    
    返回:
    
    the sizes
  - getApproximateSizes
```
public long[] getApproximateSizes(java.util.List<Range> ranges,
                                  SizeApproximationFlag... sizeApproximationFlags)
```
    Get the approximate file system space used by keys in each range for the default column family.
    Note that the returned sizes measure file system space usage, so if the user data compresses by a factor of ten, the returned sizes will be one-tenth the size of the corresponding user data size.
    If sizeApproximationFlags defines whether the returned size should include the recently written data in the mem-tables (if the mem-table type supports it), data serialized to disk, or both.
    
    参数:
    
    ranges - the ranges over which to approximate sizes
    
    sizeApproximationFlags - flags to determine what to include in the approximation.
    
    返回:
    
    the sizes.
  - getApproximateMemTableStats
```
public RocksDB.CountAndSize getApproximateMemTableStats(ColumnFamilyHandle columnFamilyHandle,
                                                        Range range)
```
    This method is similar to getApproximateSizes(ColumnFamilyHandle, List, SizeApproximationFlag...), except that it returns approximate number of records and size in memtables.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family
    
    range - the ranges over which to get the memtable stats
    
    返回:
    
    the count and size for the range
  - getApproximateMemTableStats
```
public RocksDB.CountAndSize getApproximateMemTableStats(Range range)
```
    This method is similar to getApproximateSizes(ColumnFamilyHandle, List, SizeApproximationFlag...), except that it returns approximate number of records and size in memtables.
    
    参数:
    
    range - the ranges over which to get the memtable stats
    
    返回:
    
    the count and size for the range
  - compactRange
```
public void compactRange()
                  throws RocksDBException
```
    Range compaction of database.
    
    Note: After the database has been compacted, all data will have been pushed down to the last level containing any data.
    
    See also
    - compactRange(byte[], byte[])
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - compactRange
```
public void compactRange(ColumnFamilyHandle columnFamilyHandle)
                  throws RocksDBException
```
    Range compaction of column family.
    
    Note: After the database has been compacted, all data will have been pushed down to the last level containing any data.
    
    See also
    - compactRange(ColumnFamilyHandle, byte[], byte[])
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family.
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - compactRange
```
public void compactRange(byte[] begin,
                         byte[] end)
                  throws RocksDBException
```
    Range compaction of database.
    
    Note: After the database has been compacted, all data will have been pushed down to the last level containing any data.
    
    See also
    - compactRange()
    参数:
    
    begin - start of key range (included in range)
    
    end - end of key range (excluded from range)
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - compactRange
```
public void compactRange(ColumnFamilyHandle columnFamilyHandle,
                         byte[] begin,
                         byte[] end)
                  throws RocksDBException
```
    Range compaction of column family.
    
    Note: After the database has been compacted, all data will have been pushed down to the last level containing any data.
    
    See also
    - compactRange(ColumnFamilyHandle)
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family.
    
    begin - start of key range (included in range)
    
    end - end of key range (excluded from range)
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - compactRange
```
public void compactRange(ColumnFamilyHandle columnFamilyHandle,
                         byte[] begin,
                         byte[] end,
                         CompactRangeOptions compactRangeOptions)
                  throws RocksDBException
```
    Range compaction of column family.
    
    Note: After the database has been compacted, all data will have been pushed down to the last level containing any data.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance.
    
    begin - start of key range (included in range)
    
    end - end of key range (excluded from range)
    
    compactRangeOptions - options for the compaction
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - setOptions
```
public void setOptions(ColumnFamilyHandle columnFamilyHandle,
                       MutableColumnFamilyOptions mutableColumnFamilyOptions)
                throws RocksDBException
```
    Change the options for the column family handle.
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family.
    
    mutableColumnFamilyOptions - the options.
    
    抛出:
    
    RocksDBException - if an error occurs whilst setting the options
  - getOptions
```
public MutableColumnFamilyOptions.MutableColumnFamilyOptionsBuilder getOptions(ColumnFamilyHandle columnFamilyHandle)
                                                                        throws RocksDBException
```
    Get the options for the column family handle
    
    参数:
    
    columnFamilyHandle - ColumnFamilyHandle instance, or null for the default column family.
    
    返回:
    
    the options parsed from the options string return by RocksDB
    
    抛出:
    
    RocksDBException - if an error occurs while getting the options string, or parsing the resulting options string into options
  - getOptions
```
public MutableColumnFamilyOptions.MutableColumnFamilyOptionsBuilder getOptions()
                                                                        throws RocksDBException
```
    Default column family options
    
    返回:
    
    the options parsed from the options string return by RocksDB
    
    抛出:
    
    RocksDBException - if an error occurs while getting the options string, or parsing the resulting options string into options
  - getDBOptions
```
public MutableDBOptions.MutableDBOptionsBuilder getDBOptions()
                                                      throws RocksDBException
```
    Get the database options
    
    返回:
    
    the DB options parsed from the options string return by RocksDB
    
    抛出:
    
    RocksDBException - if an error occurs while getting the options string, or parsing the resulting options string into options
  - setOptions
```
public void setOptions(MutableColumnFamilyOptions mutableColumnFamilyOptions)
                throws RocksDBException
```
    Change the options for the default column family handle.
    
    参数:
    
    mutableColumnFamilyOptions - the options.
    
    抛出:
    
    RocksDBException - if an error occurs whilst setting the options
  - setDBOptions
```
public void setDBOptions(MutableDBOptions mutableDBoptions)
                  throws RocksDBException
```
    Set the options for the column family handle.
    
    参数:
    
    mutableDBoptions - the options.
    
    抛出:
    
    RocksDBException - if an error occurs whilst setting the options
  - compactFiles
```
public java.util.List<java.lang.String> compactFiles(CompactionOptions compactionOptions,
                                                     java.util.List<java.lang.String> inputFileNames,
                                                     int outputLevel,
                                                     int outputPathId,
                                                     CompactionJobInfo compactionJobInfo)
                                              throws RocksDBException
```
    Takes a list of files specified by file names and compacts them to the specified level.
    Note that the behavior is different from compactRange(ColumnFamilyHandle, byte[], byte[]) in that CompactFiles() performs the compaction job using the CURRENT thread.
    
    参数:
    
    compactionOptions - compaction options
    
    inputFileNames - the name of the files to compact
    
    outputLevel - the level to which they should be compacted
    
    outputPathId - the id of the output path, or -1
    
    compactionJobInfo - the compaction job info, this parameter will be updated with the info from compacting the files, can just be null if you don't need it.
    
    返回:
    
    the list of compacted files
    
    抛出:
    
    RocksDBException - if an error occurs during compaction
  - compactFiles
```
public java.util.List<java.lang.String> compactFiles(CompactionOptions compactionOptions,
                                                     ColumnFamilyHandle columnFamilyHandle,
                                                     java.util.List<java.lang.String> inputFileNames,
                                                     int outputLevel,
                                                     int outputPathId,
                                                     CompactionJobInfo compactionJobInfo)
                                              throws RocksDBException
```
    Takes a list of files specified by file names and compacts them to the specified level.
    Note that the behavior is different from compactRange(ColumnFamilyHandle, byte[], byte[]) in that CompactFiles() performs the compaction job using the CURRENT thread.
    
    参数:
    
    compactionOptions - compaction options
    
    columnFamilyHandle - columnFamilyHandle, or null for the default column family
    
    inputFileNames - the name of the files to compact
    
    outputLevel - the level to which they should be compacted
    
    outputPathId - the id of the output path, or -1
    
    compactionJobInfo - the compaction job info, this parameter will be updated with the info from compacting the files, can just be null if you don't need it.
    
    返回:
    
    the list of compacted files
    
    抛出:
    
    RocksDBException - if an error occurs during compaction
  - cancelAllBackgroundWork
```
public void cancelAllBackgroundWork(boolean wait)
```
    This function will cancel all currently running background processes.
    
    参数:
    
    wait - if true, wait for all background work to be cancelled before returning.
  - pauseBackgroundWork
```
public void pauseBackgroundWork()
                         throws RocksDBException
```
    This function will wait until all currently running background processes finish. After it returns, no background process will be run until continueBackgroundWork() is called
    
    抛出:
    
    RocksDBException - if an error occurs when pausing background work
  - continueBackgroundWork
```
public void continueBackgroundWork()
                            throws RocksDBException
```
    Resumes background work which was suspended by previously calling pauseBackgroundWork()
    
    抛出:
    
    RocksDBException - if an error occurs when resuming background work
  - enableAutoCompaction
```
public void enableAutoCompaction(java.util.List<ColumnFamilyHandle> columnFamilyHandles)
                          throws RocksDBException
```
    Enable automatic compactions for the given column families if they were previously disabled.
    The function will first set the ColumnFamilyOptions.disableAutoCompactions() option for each column family to false, after which it will schedule a flush/compaction.
    NOTE: Setting disableAutoCompactions to 'false' through setOptions(ColumnFamilyHandle, MutableColumnFamilyOptions) does NOT schedule a flush/compaction afterwards, and only changes the parameter itself within the column family option.
    
    参数:
    
    columnFamilyHandles - the column family handles
    
    抛出:
    
    RocksDBException - if an error occurs whilst enabling auto-compaction
  - numberLevels
```
public int numberLevels()
```
    Number of levels used for this DB.
    
    返回:
    
    the number of levels
  - numberLevels
```
public int numberLevels(ColumnFamilyHandle columnFamilyHandle)
```
    Number of levels used for a column family in this DB.
    
    参数:
    
    columnFamilyHandle - the column family handle, or null for the default column family
    
    返回:
    
    the number of levels
  - maxMemCompactionLevel
```
public int maxMemCompactionLevel()
```
    Maximum level to which a new compacted memtable is pushed if it does not create overlap.
    
    返回:
    
    the maximum level
  - maxMemCompactionLevel
```
public int maxMemCompactionLevel(ColumnFamilyHandle columnFamilyHandle)
```
    Maximum level to which a new compacted memtable is pushed if it does not create overlap.
    
    参数:
    
    columnFamilyHandle - the column family handle
    
    返回:
    
    the maximum level
  - level0StopWriteTrigger
```
public int level0StopWriteTrigger()
```
    Number of files in level-0 that would stop writes.
    
    返回:
    
    the number of files
  - level0StopWriteTrigger
```
public int level0StopWriteTrigger(ColumnFamilyHandle columnFamilyHandle)
```
    Number of files in level-0 that would stop writes.
    
    参数:
    
    columnFamilyHandle - the column family handle
    
    返回:
    
    the number of files
  - getName
```
public java.lang.String getName()
```
    Get DB name -- the exact same name that was provided as an argument to as path to open(Options, String).
    
    返回:
    
    the DB name
  - getEnv
```
public Env getEnv()
```
    Get the Env object from the DB
    
    返回:
    
    the env
  - flush
```
public void flush(FlushOptions flushOptions)
           throws RocksDBException
```
    Flush all memory table data.
    
    Note: it must be ensured that the FlushOptions instance is not GC'ed before this method finishes. If the wait parameter is set to false, flush processing is asynchronous.
    
    参数:
    
    flushOptions - FlushOptions instance.
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - flush
```
public void flush(FlushOptions flushOptions,
                  ColumnFamilyHandle columnFamilyHandle)
           throws RocksDBException
```
    Flush all memory table data.
    
    Note: it must be ensured that the FlushOptions instance is not GC'ed before this method finishes. If the wait parameter is set to false, flush processing is asynchronous.
    
    参数:
    
    flushOptions - FlushOptions instance.
    
    columnFamilyHandle - ColumnFamilyHandle instance.
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - flush
```
public void flush(FlushOptions flushOptions,
                  java.util.List<ColumnFamilyHandle> columnFamilyHandles)
           throws RocksDBException
```
    Flushes multiple column families.
    If atomic flush is not enabled, this is equivalent to calling flush(FlushOptions, ColumnFamilyHandle) multiple times.
    If atomic flush is enabled, this will flush all column families specified up to the latest sequence number at the time when flush is requested.
    
    参数:
    
    flushOptions - FlushOptions instance.
    
    columnFamilyHandles - column family handles.
    
    抛出:
    
    RocksDBException - thrown if an error occurs within the native part of the library.
  - flushWal
```
public void flushWal(boolean sync)
              throws RocksDBException
```
    Flush the WAL memory buffer to the file. If sync is true, it calls syncWal() afterwards.
    
    参数:
    
    sync - true to also fsync to disk.
    
    抛出:
    
    RocksDBException - if an error occurs whilst flushing
  - syncWal
```
public void syncWal()
             throws RocksDBException
```
    Sync the WAL.
    Note that write(WriteOptions, WriteBatch) followed by #syncWal() is not exactly the same as write(WriteOptions, WriteBatch) with WriteOptions.sync() set to true; In the latter case the changes won't be visible until the sync is done.
    Currently only works if Options.allowMmapWrites() is set to false.
    
    抛出:
    
    RocksDBException - if an error occurs whilst syncing
  - getLatestSequenceNumber
```
public long getLatestSequenceNumber()
```
    The sequence number of the most recent transaction.
    
    返回:
    
    sequence number of the most recent transaction.
  - disableFileDeletions
```
public void disableFileDeletions()
                          throws RocksDBException
```
    Prevent file deletions. Compactions will continue to occur, but no obsolete files will be deleted. Calling this multiple times have the same effect as calling it once.
    
    抛出:
    
    RocksDBException - thrown if operation was not performed successfully.
  - enableFileDeletions
```
public void enableFileDeletions(boolean force)
                         throws RocksDBException
```
    Allow compactions to delete obsolete files. If force == true, the call to EnableFileDeletions() will guarantee that file deletions are enabled after the call, even if DisableFileDeletions() was called multiple times before.
    
    If force == false, EnableFileDeletions will only enable file deletion after it's been called at least as many times as DisableFileDeletions(), enabling the two methods to be called by two threads concurrently without synchronization -- i.e., file deletions will be enabled only after both threads call EnableFileDeletions()
    
    参数:
    
    force - boolean value described above.
    
    抛出:
    
    RocksDBException - thrown if operation was not performed successfully.
  - getLiveFiles
```
public RocksDB.LiveFiles getLiveFiles()
                               throws RocksDBException
```
    Retrieve the list of all files in the database after flushing the memtable.
    See getLiveFiles(boolean).
    
    返回:
    
    the live files
    
    抛出:
    
    RocksDBException - if an error occurs whilst retrieving the list of live files
  - getLiveFiles
```
public RocksDB.LiveFiles getLiveFiles(boolean flushMemtable)
                               throws RocksDBException
```
    Retrieve the list of all files in the database.
    In case you have multiple column families, even if flushMemtable is true, you still need to call getSortedWalFiles() after #getLiveFiles(boolean) to compensate for new data that arrived to already-flushed column families while other column families were flushing.
    NOTE: Calling #getLiveFiles(boolean) followed by getSortedWalFiles() can generate a lossless backup.
    
    参数:
    
    flushMemtable - set to true to flush before recoding the live files. Setting to false is useful when we don't want to wait for flush which may have to wait for compaction to complete taking an indeterminate time.
    
    返回:
    
    the live files
    
    抛出:
    
    RocksDBException - if an error occurs whilst retrieving the list of live files
  - getSortedWalFiles
```
public java.util.List<LogFile> getSortedWalFiles()
                                          throws RocksDBException
```
    Retrieve the sorted list of all wal files with earliest file first.
    
    返回:
    
    the log files
    
    抛出:
    
    RocksDBException - if an error occurs whilst retrieving the list of sorted WAL files
  - getUpdatesSince
```
public TransactionLogIterator getUpdatesSince(long sequenceNumber)
                                       throws RocksDBException
```
    Returns an iterator that is positioned at a write-batch containing seq_number. If the sequence number is non existent, it returns an iterator at the first available seq_no after the requested seq_no.
    
    Must set WAL_ttl_seconds or WAL_size_limit_MB to large values to use this api, else the WAL files will get cleared aggressively and the iterator might keep getting invalid before an update is read.
    
    参数:
    
    sequenceNumber - sequence number offset
    
    返回:
    
    TransactionLogIterator instance.
    
    抛出:
    
    RocksDBException - if iterator cannot be retrieved from native-side.
  - deleteFile
```
public void deleteFile(java.lang.String name)
                throws RocksDBException
```
    Delete the file name from the db directory and update the internal state to reflect that. Supports deletion of sst and log files only. 'name' must be path relative to the db directory. eg. 000001.sst, /archive/000003.log
    
    参数:
    
    name - the file name
    
    抛出:
    
    RocksDBException - if an error occurs whilst deleting the file
  - getLiveFilesMetaData
```
public java.util.List<LiveFileMetaData> getLiveFilesMetaData()
```
    Gets a list of all table files metadata.
    
    返回:
    
    table files metadata.
  - getColumnFamilyMetaData
```
public ColumnFamilyMetaData getColumnFamilyMetaData(ColumnFamilyHandle columnFamilyHandle)
```
    Obtains the meta data of the specified column family of the DB.
    
    参数:
    
    columnFamilyHandle - the column family
    
    返回:
    
    the column family metadata
  - getColumnFamilyMetaData
```
public ColumnFamilyMetaData getColumnFamilyMetaData()
```
    Obtains the meta data of the default column family of the DB.
    
    返回:
    
    the column family metadata
  - ingestExternalFile
```
public void ingestExternalFile(java.util.List<java.lang.String> filePathList,
                               IngestExternalFileOptions ingestExternalFileOptions)
                        throws RocksDBException
```
    ingestExternalFile will load a list of external SST files (1) into the DB We will try to find the lowest possible level that the file can fit in, and ingest the file into this level (2). A file that have a key range that overlap with the memtable key range will require us to Flush the memtable first before ingesting the file.
    (1) External SST files can be created using SstFileWriter (2) We will try to ingest the files to the lowest possible level even if the file compression doesn't match the level compression
    
    参数:
    
    filePathList - The list of files to ingest
    
    ingestExternalFileOptions - the options for the ingestion
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - ingestExternalFile
```
public void ingestExternalFile(ColumnFamilyHandle columnFamilyHandle,
                               java.util.List<java.lang.String> filePathList,
                               IngestExternalFileOptions ingestExternalFileOptions)
                        throws RocksDBException
```
    ingestExternalFile will load a list of external SST files (1) into the DB We will try to find the lowest possible level that the file can fit in, and ingest the file into this level (2). A file that have a key range that overlap with the memtable key range will require us to Flush the memtable first before ingesting the file.
    (1) External SST files can be created using SstFileWriter (2) We will try to ingest the files to the lowest possible level even if the file compression doesn't match the level compression
    
    参数:
    
    columnFamilyHandle - The column family for the ingested files
    
    filePathList - The list of files to ingest
    
    ingestExternalFileOptions - the options for the ingestion
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - verifyChecksum
```
public void verifyChecksum()
                    throws RocksDBException
```
    Verify checksum
    
    抛出:
    
    RocksDBException - if the checksum is not valid
  - getDefaultColumnFamily
```
public ColumnFamilyHandle getDefaultColumnFamily()
```
    Gets the handle for the default column family
    
    返回:
    
    The handle of the default column family
  - getPropertiesOfAllTables
```
public java.util.Map<java.lang.String,TableProperties> getPropertiesOfAllTables(ColumnFamilyHandle columnFamilyHandle)
                                                                         throws RocksDBException
```
    Get the properties of all tables.
    
    参数:
    
    columnFamilyHandle - the column family handle, or null for the default column family.
    
    返回:
    
    the properties
    
    抛出:
    
    RocksDBException - if an error occurs whilst getting the properties
  - getPropertiesOfAllTables
```
public java.util.Map<java.lang.String,TableProperties> getPropertiesOfAllTables()
                                                                         throws RocksDBException
```
    Get the properties of all tables in the default column family.
    
    返回:
    
    the properties
    
    抛出:
    
    RocksDBException - if an error occurs whilst getting the properties
  - getPropertiesOfTablesInRange
```
public java.util.Map<java.lang.String,TableProperties> getPropertiesOfTablesInRange(ColumnFamilyHandle columnFamilyHandle,
                                                                                    java.util.List<Range> ranges)
                                                                             throws RocksDBException
```
    Get the properties of tables in range.
    
    参数:
    
    columnFamilyHandle - the column family handle, or null for the default column family.
    
    ranges - the ranges over which to get the table properties
    
    返回:
    
    the properties
    
    抛出:
    
    RocksDBException - if an error occurs whilst getting the properties
  - getPropertiesOfTablesInRange
```
public java.util.Map<java.lang.String,TableProperties> getPropertiesOfTablesInRange(java.util.List<Range> ranges)
                                                                             throws RocksDBException
```
    Get the properties of tables in range for the default column family.
    
    参数:
    
    ranges - the ranges over which to get the table properties
    
    返回:
    
    the properties
    
    抛出:
    
    RocksDBException - if an error occurs whilst getting the properties
  - suggestCompactRange
```
public Range suggestCompactRange(ColumnFamilyHandle columnFamilyHandle)
                          throws RocksDBException
```
    Suggest the range to compact.
    
    参数:
    
    columnFamilyHandle - the column family handle, or null for the default column family.
    
    返回:
    
    the suggested range.
    
    抛出:
    
    RocksDBException - if an error occurs whilst suggesting the range
  - suggestCompactRange
```
public Range suggestCompactRange()
                          throws RocksDBException
```
    Suggest the range to compact for the default column family.
    
    返回:
    
    the suggested range.
    
    抛出:
    
    RocksDBException - if an error occurs whilst suggesting the range
  - promoteL0
```
public void promoteL0(ColumnFamilyHandle columnFamilyHandle,
                      int targetLevel)
               throws RocksDBException
```
    Promote L0.
    
    参数:
    
    columnFamilyHandle - the column family handle, or null for the default column family.
    
    targetLevel - the target level for L0
    
    抛出:
    
    RocksDBException - if an error occurs whilst promoting L0
  - promoteL0
```
public void promoteL0(int targetLevel)
               throws RocksDBException
```
    Promote L0 for the default column family.
    
    参数:
    
    targetLevel - the target level for L0
    
    抛出:
    
    RocksDBException - if an error occurs whilst promoting L0
  - startTrace
```
public void startTrace(TraceOptions traceOptions,
                       AbstractTraceWriter traceWriter)
                throws RocksDBException
```
    Trace DB operations.
    Use endTrace() to stop tracing.
    
    参数:
    
    traceOptions - the options
    
    traceWriter - the trace writer
    
    抛出:
    
    RocksDBException - if an error occurs whilst starting the trace
  - endTrace
```
public void endTrace()
              throws RocksDBException
```
    Stop tracing DB operations.
    See startTrace(TraceOptions, AbstractTraceWriter)
    
    抛出:
    
    RocksDBException - if an error occurs whilst ending the trace
  - tryCatchUpWithPrimary
```
public void tryCatchUpWithPrimary()
                           throws RocksDBException
```
    Make the secondary instance catch up with the primary by tailing and replaying the MANIFEST and WAL of the primary. Column families created by the primary after the secondary instance starts will be ignored unless the secondary instance closes and restarts with the newly created column families. Column families that exist before secondary instance starts and dropped by the primary afterwards will be marked as dropped. However, as long as the secondary instance does not delete the corresponding column family handles, the data of the column family is still accessible to the secondary.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - deleteFilesInRanges
```
public void deleteFilesInRanges(ColumnFamilyHandle columnFamily,
                                java.util.List<byte[]> ranges,
                                boolean includeEnd)
                         throws RocksDBException
```
    Delete files in multiple ranges at once. Delete files in a lot of ranges one at a time can be slow, use this API for better performance in that case.
    
    参数:
    
    columnFamily - - The column family for operation (null for default)
    
    includeEnd - - Whether ranges should include end
    
    ranges - - pairs of ranges (from1, to1, from2, to2, ...)
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - destroyDB
```
public static void destroyDB(java.lang.String path,
                             Options options)
                      throws RocksDBException
```
    Static method to destroy the contents of the specified database. Be very careful using this method.
    
    参数:
    
    path - the path to the Rocksdb database.
    
    options - Options instance.
    
    抛出:
    
    RocksDBException - thrown if error happens in underlying native library.
  - storeOptionsInstance
```
protected void storeOptionsInstance(DBOptionsInterface<?> options)
```
  - disposeInternal
```
protected void disposeInternal(long handle)
```
    指定者:
    
    disposeInternal 在类中 RocksObject

类 RocksDB

嵌套类概要

字段概要

从类继承的字段 org.rocksdb.RocksObject

从类继承的字段 org.rocksdb.AbstractImmutableNativeReference

构造器概要

方法概要

从类继承的方法 org.rocksdb.RocksObject

从类继承的方法 org.rocksdb.AbstractImmutableNativeReference

从类继承的方法 java.lang.Object

字段详细资料

DEFAULT_COLUMN_FAMILY

NOT_FOUND

options_

构造器详细资料

RocksDB

方法详细资料

loadLibrary

loadLibrary

rocksdbVersion

open

open

open

open

openReadOnly

openReadOnly

openReadOnly

openReadOnly

openReadOnly

openReadOnly

openAsSecondary

openAsSecondary

closeE

close

listColumnFamilies

createColumnFamily

createColumnFamilies

createColumnFamilies

dropColumnFamily

dropColumnFamilies

destroyColumnFamilyHandle

put

put

put

put

put

put

put

put

put

put

delete

delete

delete

delete

delete

delete

delete

delete

get

get

singleDelete

singleDelete

singleDelete

singleDelete

deleteRange

deleteRange

deleteRange

deleteRange

merge

merge

merge

merge

merge

merge

delete

delete

merge

merge

write