org.h2.index

Class Index

java.lang.Object

org.h2.engine.DbObject

org.h2.schema.SchemaObject

org.h2.index.Index

All Implemented Interfaces:

HasSQL

Direct Known Subclasses:

LinkedIndex, MetaIndex, MVIndex, QueryExpressionIndex, VirtualTableIndex

public abstract class Index
extends SchemaObject

An index. Indexes are used to speed up searching data.

Field Summary

Fields

Modifier and Type	Field and Description
protected int[]	columnIds Identities of table columns.
protected Column[]	columns Table columns used in this index.
protected IndexColumn[]	indexColumns Columns of this index.
protected IndexType	indexType The index type.
protected Table	table The table.
protected int	uniqueColumnColumn Count of unique columns.

Fields inherited from class org.h2.engine.DbObject

AGGREGATE, comment, COMMENT, CONSTANT, CONSTRAINT, database, DOMAIN, FUNCTION_ALIAS, INDEX, RIGHT, ROLE, SCHEMA, SEQUENCE, SETTING, SYNONYM, TABLE_OR_VIEW, trace, TRIGGER, USER

Fields inherited from interface org.h2.util.HasSQL

ADD_PLAN_INFORMATION, DEFAULT_SQL_FLAGS, NO_CASTS, QUOTE_ONLY_WHEN_REQUIRED, REPLACE_LOBS_FOR_TRACE, TRACE_SQL_FLAGS

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Index(Table newTable, int id, java.lang.String name, IndexColumn[] newIndexColumns, int uniqueColumnCount, IndexType newIndexType) Initialize the index.

Method Summary

Modifier and Type	Method and Description
abstract void	add(SessionLocal session, Row row) Add a row to the index.
boolean	canFindNext() Check if the index can get the next higher value.
boolean	canGetFirstOrLast() Check if the index can directly look up the lowest or highest value of a column.
boolean	canScan() Can this index iterate over all rows?
protected static void	checkIndexColumnTypes(IndexColumn[] columns) Check that the index columns are not CLOB or BLOB.
abstract void	close(SessionLocal session) Close this index.
int	compareRows(SearchRow rowData, SearchRow compare) Compare two rows.
abstract Cursor	find(SessionLocal session, SearchRow first, SearchRow last) Find a row or a list of rows and create a cursor to iterate over the result.
Cursor	findFirstOrLast(SessionLocal session, boolean first) Find the first (or last) value of this index.
Cursor	findNext(SessionLocal session, SearchRow higherThan, SearchRow last) Find a row or a list of rows that is larger and create a cursor to iterate over the result.
int	getColumnIndex(Column col) Get the index of a column in the list of index columns
Column[]	getColumns() Get the indexed columns.
abstract double	getCost(SessionLocal session, int[] masks, TableFilter[] filters, int filter, SortOrder sortOrder, AllColumnsForPlan allColumnsSet) Estimate the cost to search for rows given the search mask.
protected long	getCostRangeIndex(int[] masks, long rowCount, TableFilter[] filters, int filter, SortOrder sortOrder, boolean isScanIndex, AllColumnsForPlan allColumnsSet) Calculate the cost for the given mask as if this index was a typical b-tree range index.
java.lang.String	getCreateSQL() Construct the CREATE ...
java.lang.String	getCreateSQLForCopy(Table targetTable, java.lang.String quotedName) Build a SQL statement to re-create the object, or to create a copy of the object with a different name or referencing a different table
long	getDiskSpaceUsed() Get the used disk space for this index.
DbException	getDuplicateKeyException(java.lang.String key) Create a duplicate key exception with a message that contains the index name.
protected java.lang.StringBuilder	getDuplicatePrimaryKeyMessage(int mainIndexColumn) Get "PRIMARY KEY ON <table> [(column)]".
IndexColumn[]	getIndexColumns() Get the indexed columns as index columns (with ordering information).
IndexType	getIndexType() Get the index type.
java.lang.String	getPlanSQL() Get the message to show in a EXPLAIN statement.
Row	getRow(SessionLocal session, long key) Get the row with the given key.
abstract long	getRowCount(SessionLocal session) Get the row count of this table, for the given session.
abstract long	getRowCountApproximation(SessionLocal session) Get the approximated row count for this table.
RowFactory	getRowFactory()
Table	getTable() Get the table on which this index is based.
int	getType() Get the object type.
int	getUniqueColumnCount() Returns count of unique columns.
RowFactory	getUniqueRowFactory()
boolean	isFindUsingFullTableScan() Returns true if find() implementation performs scan over all index, false if find() performs the fast lookup.
boolean	isFirstColumn(Column column) Check if the given column is the first for this index
boolean	isHidden() Check whether this is a hidden object that doesn't appear in the meta data and in the script, and is not dropped on DROP ALL OBJECTS.
boolean	isRowIdIndex() Does this index support lookup by row id?
boolean	mayHaveNullDuplicates(SearchRow searchRow) Check if this row may have duplicates with the same indexed values in the current compatibility mode.
abstract boolean	needRebuild() Check if the index needs to be rebuilt.
abstract void	remove(SessionLocal session) Remove the index.
abstract void	remove(SessionLocal session, Row row) Remove a row from the index.
void	removeChildrenAndResources(SessionLocal session) Delete all dependent children objects and resources of this object.
abstract void	truncate(SessionLocal session) Remove all rows from the index.
void	update(SessionLocal session, Row oldRow, Row newRow) Update index after row change.

Methods inherited from class org.h2.schema.SchemaObject

getSchema, getSQL, getSQL

Methods inherited from class org.h2.engine.DbObject

checkRename, getChildren, getComment, getCreateSQLForMeta, getDatabase, getDropSQL, getId, getModificationId, getName, invalidate, isTemporary, isValid, rename, setComment, setModified, setObjectName, setTemporary, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.h2.util.HasSQL

getTraceSQL

Field Detail

indexColumns

protected IndexColumn[] indexColumns

Columns of this index.

columns

protected Column[] columns

Table columns used in this index.

columnIds

protected int[] columnIds

Identities of table columns.

uniqueColumnColumn

protected final int uniqueColumnColumn

Count of unique columns. Unique columns, if any, are always first columns in the lists.

table

protected final Table table

The table.

indexType

protected final IndexType indexType

The index type.

Constructor Detail

Index

protected Index(Table newTable,
                int id,
                java.lang.String name,
                IndexColumn[] newIndexColumns,
                int uniqueColumnCount,
                IndexType newIndexType)

Initialize the index.

Parameters:

newTable - the table

id - the object id

name - the index name

newIndexColumns - the columns that are indexed or null if this is not yet known

uniqueColumnCount - count of unique columns

newIndexType - the index type

Method Detail

checkIndexColumnTypes

protected static void checkIndexColumnTypes(IndexColumn[] columns)

Check that the index columns are not CLOB or BLOB.

Parameters:

columns - the columns

getType

public final int getType()

Description copied from class: DbObject

Get the object type.

Specified by:

getType in class DbObject

Returns:

the object type

removeChildrenAndResources

public void removeChildrenAndResources(SessionLocal session)

Description copied from class: DbObject

Delete all dependent children objects and resources of this object.

Specified by:

removeChildrenAndResources in class DbObject

Parameters:

session - the session

isHidden

public final boolean isHidden()

Description copied from class: SchemaObject

Check whether this is a hidden object that doesn't appear in the meta data and in the script, and is not dropped on DROP ALL OBJECTS.

Overrides:

isHidden in class SchemaObject

Returns:

true if it is hidden

getCreateSQLForCopy

public java.lang.String getCreateSQLForCopy(Table targetTable,
                                            java.lang.String quotedName)

Description copied from class: DbObject

Build a SQL statement to re-create the object, or to create a copy of the object with a different name or referencing a different table

Overrides:

getCreateSQLForCopy in class DbObject

Parameters:

targetTable - the new table

quotedName - the quoted name

Returns:

the SQL statement

getCreateSQL

public java.lang.String getCreateSQL()

Description copied from class: DbObject

Construct the CREATE ... SQL statement for this object.

Specified by:

getCreateSQL in class DbObject

Returns:

the SQL statement

getPlanSQL

public java.lang.String getPlanSQL()

Get the message to show in a EXPLAIN statement.

Returns:

the plan

close

public abstract void close(SessionLocal session)

Close this index.

Parameters:

session - the session used to write data

add

public abstract void add(SessionLocal session,
                         Row row)

Add a row to the index.

Parameters:

session - the session to use

row - the row to add

remove

public abstract void remove(SessionLocal session,
                            Row row)

Remove a row from the index.

Parameters:

session - the session

row - the row

update

public void update(SessionLocal session,
                   Row oldRow,
                   Row newRow)

Update index after row change.

Parameters:

session - the session

oldRow - row before the update

newRow - row after the update

isFindUsingFullTableScan

public boolean isFindUsingFullTableScan()

Returns true if find() implementation performs scan over all index, false if find() performs the fast lookup.

Returns:

true if find() implementation performs scan over all index, false if find() performs the fast lookup

find

public abstract Cursor find(SessionLocal session,
                            SearchRow first,
                            SearchRow last)

Find a row or a list of rows and create a cursor to iterate over the result.

Parameters:

session - the session

first - the first row, or null for no limit

last - the last row, or null for no limit

Returns:

the cursor to iterate over the results

getCost

public abstract double getCost(SessionLocal session,
                               int[] masks,
                               TableFilter[] filters,
                               int filter,
                               SortOrder sortOrder,
                               AllColumnsForPlan allColumnsSet)

Estimate the cost to search for rows given the search mask. There is one element per column in the search mask. For possible search masks, see IndexCondition.

Parameters:

session - the session

masks - per-column comparison bit masks, null means 'always false', see constants in IndexCondition

filters - all joined table filters

filter - the current table filter index

sortOrder - the sort order

allColumnsSet - the set of all columns

Returns:

the estimated cost

remove

public abstract void remove(SessionLocal session)

Remove the index.

Parameters:

session - the session

truncate

public abstract void truncate(SessionLocal session)

Remove all rows from the index.

Parameters:

session - the session

canGetFirstOrLast

public boolean canGetFirstOrLast()

Check if the index can directly look up the lowest or highest value of a column.

Returns:

true if it can

canFindNext

public boolean canFindNext()

Check if the index can get the next higher value.

Returns:

true if it can

findNext

public Cursor findNext(SessionLocal session,
                       SearchRow higherThan,
                       SearchRow last)

Find a row or a list of rows that is larger and create a cursor to iterate over the result.

Parameters:

session - the session

higherThan - the lower limit (excluding)

last - the last row, or null for no limit

Returns:

the cursor

findFirstOrLast

public Cursor findFirstOrLast(SessionLocal session,
                              boolean first)

Find the first (or last) value of this index. The cursor returned is positioned on the correct row, or on null if no row has been found.

Parameters:

session - the session

first - true if the first (lowest for ascending indexes) or last value should be returned

Returns:

a cursor (never null)

needRebuild

public abstract boolean needRebuild()

Check if the index needs to be rebuilt. This method is called after opening an index.

Returns:

true if a rebuild is required.

getRowCount

public abstract long getRowCount(SessionLocal session)

Get the row count of this table, for the given session.

Parameters:

session - the session

Returns:

the row count

getRowCountApproximation

public abstract long getRowCountApproximation(SessionLocal session)

Get the approximated row count for this table.

Parameters:

session - the session

Returns:

the approximated row count

getDiskSpaceUsed

public long getDiskSpaceUsed()

Get the used disk space for this index.

Returns:

the estimated number of bytes

compareRows

public final int compareRows(SearchRow rowData,
                             SearchRow compare)

Compare two rows.

Parameters:

rowData - the first row

compare - the second row

Returns:

0 if both rows are equal, -1 if the first row is smaller, otherwise 1

getColumnIndex

public int getColumnIndex(Column col)

Get the index of a column in the list of index columns

Parameters:

col - the column

Returns:

the index (0 meaning first column)

isFirstColumn

public boolean isFirstColumn(Column column)

Check if the given column is the first for this index

Parameters:

column - the column

Returns:

true if the given columns is the first

getIndexColumns

public final IndexColumn[] getIndexColumns()

Get the indexed columns as index columns (with ordering information).

Returns:

the index columns

getColumns

public final Column[] getColumns()

Get the indexed columns.

Returns:

the columns

getUniqueColumnCount

public final int getUniqueColumnCount()

Returns count of unique columns. Unique columns, if any, are always first columns in the lists. Unique indexes may have additional indexed non-unique columns.

Returns:

count of unique columns, or 0 if index isn't unique

getIndexType

public final IndexType getIndexType()

Get the index type.

Returns:

the index type

getTable

public Table getTable()

Get the table on which this index is based.

Returns:

the table

getRow

public Row getRow(SessionLocal session,
                  long key)

Get the row with the given key.

Parameters:

session - the session

key - the unique key

Returns:

the row

isRowIdIndex

public boolean isRowIdIndex()

Does this index support lookup by row id?

Returns:

true if it does

canScan

public boolean canScan()

Can this index iterate over all rows?

Returns:

true if it can

getDuplicateKeyException

public DbException getDuplicateKeyException(java.lang.String key)

Create a duplicate key exception with a message that contains the index name.

Parameters:

key - the key values

Returns:

the exception

getDuplicatePrimaryKeyMessage

protected java.lang.StringBuilder getDuplicatePrimaryKeyMessage(int mainIndexColumn)

Get "PRIMARY KEY ON <table> [(column)]".

Parameters:

mainIndexColumn - the column index

Returns:

the message

getCostRangeIndex

protected final long getCostRangeIndex(int[] masks,
                                       long rowCount,
                                       TableFilter[] filters,
                                       int filter,
                                       SortOrder sortOrder,
                                       boolean isScanIndex,
                                       AllColumnsForPlan allColumnsSet)

Calculate the cost for the given mask as if this index was a typical b-tree range index. This is the estimated cost required to search one row, and then iterate over the given number of rows.

Parameters:

masks - the IndexCondition search masks, one for each column in the table

rowCount - the number of rows in the index

filters - all joined table filters

filter - the current table filter index

sortOrder - the sort order

isScanIndex - whether this is a "table scan" index

allColumnsSet - the set of all columns

Returns:

the estimated cost

mayHaveNullDuplicates

public final boolean mayHaveNullDuplicates(SearchRow searchRow)

Check if this row may have duplicates with the same indexed values in the current compatibility mode. Duplicates with NULL values are allowed in some modes.

Parameters:

searchRow - the row to check

Returns:

true if specified row may have duplicates, false otherwise

getRowFactory

public RowFactory getRowFactory()

getUniqueRowFactory

public RowFactory getUniqueRowFactory()