org.h2.index
Class HashIndex

java.lang.Object
  org.h2.engine.DbObjectBase
      org.h2.schema.SchemaObjectBase
          org.h2.index.BaseIndex
              org.h2.index.HashIndex

All Implemented Interfaces:

DbObject, Index, SchemaObject

Direct Known Subclasses:

NonUniqueHashIndex

public class HashIndex
extends BaseIndex

An unique index based on an in-memory hash map.

Field Summary

protected int

indexColumn The index of the indexed column.

Fields inherited from class org.h2.index.BaseIndex

columnIds, columns, indexColumns, indexType, isMultiVersion, table

Fields inherited from class org.h2.engine.DbObjectBase

comment, database, trace

Fields inherited from interface org.h2.engine.DbObject

AGGREGATE, COMMENT, CONSTANT, CONSTRAINT, FUNCTION_ALIAS, INDEX, RIGHT, ROLE, SCHEMA, SEQUENCE, SETTING, TABLE_OR_VIEW, TRIGGER, USER, USER_DATATYPE

Constructor Summary

HashIndex(RegularTable table, int id, java.lang.String indexName, IndexColumn[] columns, IndexType indexType)

Method Summary

void	add(Session session, Row row) Add a row to this index.
boolean	canGetFirstOrLast() Check if this index can quickly find the first or last value.
void	checkRename() Check if this object can be renamed.
void	close(Session session) Close this index.
Cursor	find(Session session, SearchRow first, SearchRow last) Create a cursor to iterate over a number of rows.
Cursor	findFirstOrLast(Session session, boolean first) Find the first (or last) value of this index.
double	getCost(Session session, int[] masks) Calculate the cost to find rows.
long	getRowCount(Session session) Get the row count of this table, for the given session.
long	getRowCountApproximation() Get the approximated row count for this table.
boolean	needRebuild() Check if this index needs to be re-built.
void	remove(Session session) Remove the index.
void	remove(Session session, Row row) Remove a row from the index.
void	truncate(Session session) Truncate the index.

Methods inherited from class org.h2.index.BaseIndex

canFindNext, commit, compareKeys, compareRows, containsNullAndAllowMultipleNull, findNext, getColumnIndex, getColumnListSQL, getColumns, getCostRangeIndex, getCreateSQL, getCreateSQLForCopy, getDropSQL, getDuplicateKeyException, getIndexColumns, getIndexType, getLookupCost, getPlanSQL, getRootPageId, getRow, getTable, getType, initBaseIndex, isHidden, removeChildrenAndResources

Methods inherited from class org.h2.schema.SchemaObjectBase

getSchema, getSQL, initSchemaObjectBase

Methods inherited from class org.h2.engine.DbObjectBase

getChildren, getComment, getDatabase, getId, getModificationId, getName, initDbObjectBase, invalidate, isTemporary, 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.schema.SchemaObject

getSchema

Methods inherited from interface org.h2.engine.DbObject

getChildren, getComment, getDatabase, getId, getModificationId, getName, getSQL, isTemporary, rename, setComment, setModified, setTemporary

Field Detail

indexColumn

protected final int indexColumn

The index of the indexed column.

Constructor Detail

HashIndex

public HashIndex(RegularTable table,
                 int id,
                 java.lang.String indexName,
                 IndexColumn[] columns,
                 IndexType indexType)

Method Detail

truncate

public void truncate(Session session)

Description copied from class: BaseIndex

Truncate the index.

Specified by:

truncate in interface Index

Specified by:

truncate in class BaseIndex

Parameters:

session - the session

add

public void add(Session session,
                Row row)

Description copied from class: BaseIndex

Add a row to this index.

Specified by:

add in interface Index

Specified by:

add in class BaseIndex

Parameters:

session - the session

row - the row to add

remove

public void remove(Session session,
                   Row row)

Description copied from class: BaseIndex

Remove a row from the index.

Specified by:

remove in interface Index

Specified by:

remove in class BaseIndex

Parameters:

session - the session

row - the row

find

public Cursor find(Session session,
                   SearchRow first,
                   SearchRow last)

Description copied from class: BaseIndex

Create a cursor to iterate over a number of rows.

Specified by:

find in interface Index

Specified by:

find in class BaseIndex

Parameters:

session - the session

first - the first row to return (null if no limit)

last - the last row to return (null if no limit)

Returns:

the cursor to iterate over the results

getRowCount

public long getRowCount(Session session)

Description copied from interface: Index

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

Parameters:

session - the session

Returns:

the row count

getRowCountApproximation

public long getRowCountApproximation()

Description copied from interface: Index

Get the approximated row count for this table.

Returns:

the approximated row count

close

public void close(Session session)

Description copied from class: BaseIndex

Close this index.

Specified by:

close in interface Index

Specified by:

close in class BaseIndex

Parameters:

session - the session

remove

public void remove(Session session)

Description copied from class: BaseIndex

Remove the index.

Specified by:

remove in interface Index

Specified by:

remove in class BaseIndex

Parameters:

session - the session

getCost

public double getCost(Session session,
                      int[] masks)

Description copied from class: BaseIndex

Calculate the cost to find rows.

Specified by:

getCost in interface Index

Specified by:

getCost in class BaseIndex

Parameters:

session - the session

masks - the condition mask

Returns:

the cost

checkRename

public void checkRename()

Description copied from class: DbObjectBase

Check if this object can be renamed. System objects may not be renamed.

Specified by:

checkRename in interface DbObject

Specified by:

checkRename in class DbObjectBase

needRebuild

public boolean needRebuild()

Description copied from class: BaseIndex

Check if this index needs to be re-built.

Specified by:

needRebuild in interface Index

Specified by:

needRebuild in class BaseIndex

Returns:

true if it must be re-built.

canGetFirstOrLast

public boolean canGetFirstOrLast()

Description copied from class: BaseIndex

Check if this index can quickly find the first or last value.

Specified by:

canGetFirstOrLast in interface Index

Specified by:

canGetFirstOrLast in class BaseIndex

Returns:

true if it can

findFirstOrLast

public Cursor findFirstOrLast(Session session,
                              boolean first)

Description copied from class: BaseIndex

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.

Specified by:

findFirstOrLast in interface Index

Specified by:

findFirstOrLast in class BaseIndex

Parameters:

session - the session

first - true for the first value, false for the last

Returns:

a cursor (never null)