WriteOptions

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

所有已实现的接口:

java.lang.AutoCloseable
```
public class WriteOptions
extends RocksObject
```
Options that control write operations.
Note that developers should call WriteOptions.dispose() to release the c++ side memory before a WriteOptions instance runs out of scope.

字段概要
- 从类继承的字段 org.rocksdb.RocksObject
  nativeHandle_
- 从类继承的字段 org.rocksdb.AbstractImmutableNativeReference
  owningHandle_

构造器概要

构造器
构造器和说明

WriteOptions()
Construct WriteOptions instance.

WriteOptions(WriteOptions other)
Copy constructor for WriteOptions.

构造器
构造器和说明
`WriteOptions()` Construct WriteOptions instance.
`WriteOptions(WriteOptions other)` Copy constructor for WriteOptions.

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`boolean`	`disableWAL()` If true, writes will not first go to the write ahead log, and the write may got lost after a crash.
`protected void`	`disposeInternal(long handle)`
`boolean`	`ignoreMissingColumnFamilies()` If true and if user is trying to write to column families that don't exist (they were dropped), ignore the write (don't return an error).
`boolean`	`lowPri()` Returns true if this write request is of lower priority if compaction is behind.
`boolean`	`memtableInsertHintPerBatch()` If true, this writebatch will maintain the last insert positions of each memtable as hints in concurrent write.
`boolean`	`noSlowdown()` If true and we need to wait or sleep for the write request, fails immediately with `Status.Code.Incomplete`.
`WriteOptions`	`setDisableWAL(boolean flag)` If true, writes will not first go to the write ahead log, and the write may got lost after a crash.
`WriteOptions`	`setIgnoreMissingColumnFamilies(boolean ignoreMissingColumnFamilies)` If true and if user is trying to write to column families that don't exist (they were dropped), ignore the write (don't return an error).
`WriteOptions`	`setLowPri(boolean lowPri)` If true, this write request is of lower priority if compaction is behind.
`WriteOptions`	`setMemtableInsertHintPerBatch(boolean memtableInsertHintPerBatch)` If true, this writebatch will maintain the last insert positions of each memtable as hints in concurrent write.
`WriteOptions`	`setNoSlowdown(boolean noSlowdown)` If true and we need to wait or sleep for the write request, fails immediately with `Status.Code.Incomplete`.
`WriteOptions`	`setSync(boolean flag)` If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete.
`boolean`	`sync()` If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete.

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

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

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

- 构造器详细资料
  - WriteOptions
```
public WriteOptions()
```
    Construct WriteOptions instance.
  - WriteOptions
```
public WriteOptions(WriteOptions other)
```
    Copy constructor for WriteOptions.
    NOTE: This does a shallow copy, which means comparator, merge_operator, compaction_filter, compaction_filter_factory and other pointers will be cloned!
    
    参数:
    
    other - The ColumnFamilyOptions to copy.
- 方法详细资料
  - setSync
```
public WriteOptions setSync(boolean flag)
```
    If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete. If this flag is true, writes will be slower.
    If this flag is false, and the machine crashes, some recent writes may be lost. Note that if it is just the process that crashes (i.e., the machine does not reboot), no writes will be lost even if sync==false.
    In other words, a DB write with sync==false has similar crash semantics as the "write()" system call. A DB write with sync==true has similar crash semantics to a "write()" system call followed by "fdatasync()".
    Default: false
    
    参数:
    
    flag - a boolean flag to indicate whether a write should be synchronized.
    
    返回:
    
    the instance of the current WriteOptions.
  - sync
```
public boolean sync()
```
    If true, the write will be flushed from the operating system buffer cache (by calling WritableFile::Sync()) before the write is considered complete. If this flag is true, writes will be slower.
    If this flag is false, and the machine crashes, some recent writes may be lost. Note that if it is just the process that crashes (i.e., the machine does not reboot), no writes will be lost even if sync==false.
    In other words, a DB write with sync==false has similar crash semantics as the "write()" system call. A DB write with sync==true has similar crash semantics to a "write()" system call followed by "fdatasync()".
    
    返回:
    
    boolean value indicating if sync is active.
  - setDisableWAL
```
public WriteOptions setDisableWAL(boolean flag)
```
    If true, writes will not first go to the write ahead log, and the write may got lost after a crash. The backup engine relies on write-ahead logs to back up the memtable, so if you disable write-ahead logs, you must create backups with flush_before_backup=true to avoid losing unflushed memtable data.
    
    参数:
    
    flag - a boolean flag to specify whether to disable write-ahead-log on writes.
    
    返回:
    
    the instance of the current WriteOptions.
  - disableWAL
```
public boolean disableWAL()
```
    If true, writes will not first go to the write ahead log, and the write may got lost after a crash. The backup engine relies on write-ahead logs to back up the memtable, so if you disable write-ahead logs, you must create backups with flush_before_backup=true to avoid losing unflushed memtable data.
    
    返回:
    
    boolean value indicating if WAL is disabled.
  - setIgnoreMissingColumnFamilies
```
public WriteOptions setIgnoreMissingColumnFamilies(boolean ignoreMissingColumnFamilies)
```
    If true and if user is trying to write to column families that don't exist (they were dropped), ignore the write (don't return an error). If there are multiple writes in a WriteBatch, other writes will succeed.
    Default: false
    
    参数:
    
    ignoreMissingColumnFamilies - true to ignore writes to column families which don't exist
    
    返回:
    
    the instance of the current WriteOptions.
  - ignoreMissingColumnFamilies
```
public boolean ignoreMissingColumnFamilies()
```
    If true and if user is trying to write to column families that don't exist (they were dropped), ignore the write (don't return an error). If there are multiple writes in a WriteBatch, other writes will succeed.
    Default: false
    
    返回:
    
    true if writes to column families which don't exist are ignored
  - setNoSlowdown
```
public WriteOptions setNoSlowdown(boolean noSlowdown)
```
    If true and we need to wait or sleep for the write request, fails immediately with Status.Code.Incomplete.
    
    参数:
    
    noSlowdown - true to fail write requests if we need to wait or sleep
    
    返回:
    
    the instance of the current WriteOptions.
  - noSlowdown
```
public boolean noSlowdown()
```
    If true and we need to wait or sleep for the write request, fails immediately with Status.Code.Incomplete.
    
    返回:
    
    true when write requests are failed if we need to wait or sleep
  - setLowPri
```
public WriteOptions setLowPri(boolean lowPri)
```
    If true, this write request is of lower priority if compaction is behind. In the case that, noSlowdown() == true, the request will be cancelled immediately with Status.Code.Incomplete returned. Otherwise, it will be slowed down. The slowdown value is determined by RocksDB to guarantee it introduces minimum impacts to high priority writes.
    Default: false
    
    参数:
    
    lowPri - true if the write request should be of lower priority than compactions which are behind.
    
    返回:
    
    the instance of the current WriteOptions.
  - lowPri
```
public boolean lowPri()
```
    Returns true if this write request is of lower priority if compaction is behind.
    See setLowPri(boolean).
    
    返回:
    
    true if this write request is of lower priority, false otherwise.
  - memtableInsertHintPerBatch
```
public boolean memtableInsertHintPerBatch()
```
    If true, this writebatch will maintain the last insert positions of each memtable as hints in concurrent write. It can improve write performance in concurrent writes if keys in one writebatch are sequential. In non-concurrent writes (when concurrent_memtable_writes is false) this option will be ignored.
    Default: false
    
    返回:
    
    true if writebatch will maintain the last insert positions of each memtable as hints in concurrent write.
  - setMemtableInsertHintPerBatch
```
public WriteOptions setMemtableInsertHintPerBatch(boolean memtableInsertHintPerBatch)
```
    If true, this writebatch will maintain the last insert positions of each memtable as hints in concurrent write. It can improve write performance in concurrent writes if keys in one writebatch are sequential. In non-concurrent writes (when concurrent_memtable_writes is false) this option will be ignored.
    Default: false
    
    参数:
    
    memtableInsertHintPerBatch - true if writebatch should maintain the last insert positions of each memtable as hints in concurrent write.
    
    返回:
    
    the instance of the current WriteOptions.
  - disposeInternal
```
protected final void disposeInternal(long handle)
```
    指定者:
    
    disposeInternal 在类中 RocksObject

类 WriteOptions

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

构造器详细资料

WriteOptions

WriteOptions

方法详细资料

setSync

sync

setDisableWAL

disableWAL

setIgnoreMissingColumnFamilies

ignoreMissingColumnFamilies

setNoSlowdown

noSlowdown

setLowPri

lowPri

memtableInsertHintPerBatch

setMemtableInsertHintPerBatch

disposeInternal