org.h2.index

Class ScanIndex

java.lang.Object

org.h2.engine.DbObjectBase

org.h2.schema.SchemaObjectBase

org.h2.index.BaseIndex

org.h2.index.ScanIndex

All Implemented Interfaces:

DbObject, Index, SchemaObject

public class ScanIndex
extends BaseIndex

The scan index is not really an 'index' in the strict sense, because it can not be used for direct lookup. It can only be used to iterate over all rows of a table. Each regular table has one such object, even if no primary key or indexes are defined.

Field Summary

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

Constructors

Constructor and Description
ScanIndex(RegularTable table, int id, IndexColumn[] columns, IndexType indexType)

Method Summary

Methods

Modifier and Type	Method and Description
void	add(Session session, Row row) Add a row to the index.
boolean	canGetFirstOrLast() Check if the index can directly look up the lowest or highest value of a column.
void	checkRename() Check if this object can be renamed.
void	close(Session session) Close this index.
void	commit(int operation, Row row) Commit the operation for a row.
Cursor	find(Session session, SearchRow first, SearchRow last) Find a row or a list of rows and create a cursor to iterate over the result.
Cursor	findFirstOrLast(Session session, boolean first) Find the first (or last) value of this index.
int	getColumnIndex(Column col) Get the index of a column in the list of index columns
double	getCost(Session session, int[] masks) Estimate the cost to search for rows given the search mask.
String	getCreateSQL() Build a SQL statement to re-create this object.
String	getPlanSQL() Get the message to show in a EXPLAIN statement.
Row	getRow(Session session, long key) Get the row with the given key.
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 the index needs to be rebuilt.
void	remove(Session session) Remove the index.
void	remove(Session session, Row row) Remove a row from the index.
void	truncate(Session session) Remove all rows from the index.

Methods inherited from class org.h2.index.BaseIndex

canFindNext, canScan, compareRows, find, findNext, getColumns, getCreateSQLForCopy, getDropSQL, getIndexColumns, getIndexType, getTable, getType, initBaseIndex, isHidden, isRowIdIndex, removeChildrenAndResources, setSortedInsertMode

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, getName, getSQL, isTemporary, rename, setComment, setTemporary

Constructor Detail

ScanIndex

public ScanIndex(RegularTable table,
         int id,
         IndexColumn[] columns,
         IndexType indexType)

Method Detail

remove

public void remove(Session session)

Description copied from interface: Index

Remove the index.

Parameters:

session - the session

truncate

public void truncate(Session session)

Description copied from interface: Index

Remove all rows from the index.

Parameters:

session - the session

getCreateSQL

public String getCreateSQL()

Description copied from class: DbObjectBase

Build a SQL statement to re-create this object.

Specified by:

getCreateSQL in interface DbObject

Overrides:

getCreateSQL in class BaseIndex

Returns:

the SQL statement

close

public void close(Session session)

Description copied from interface: Index

Close this index.

Parameters:

session - the session used to write data

getRow

public Row getRow(Session session,
         long key)

Description copied from interface: Index

Get the row with the given key.

Specified by:

getRow in interface Index

Overrides:

getRow in class BaseIndex

Parameters:

session - the session

key - the unique key

Returns:

the row

add

public void add(Session session,
       Row row)

Description copied from interface: Index

Add a row to the index.

Parameters:

session - the session to use

row - the row to add

commit

public void commit(int operation,
          Row row)

Description copied from interface: Index

Commit the operation for a row. This is only important for multi-version indexes.

Specified by:

commit in interface Index

Overrides:

commit in class BaseIndex

Parameters:

operation - the operation type

row - the row

remove

public void remove(Session session,
          Row row)

Description copied from interface: Index

Remove a row from the index.

Parameters:

session - the session

row - the row

find

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

Description copied from interface: Index

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 double getCost(Session session,
             int[] masks)

Description copied from interface: Index

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 - the search mask

Returns:

the estimated cost

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

getColumnIndex

public int getColumnIndex(Column col)

Description copied from interface: Index

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

Specified by:

getColumnIndex in interface Index

Overrides:

getColumnIndex in class BaseIndex

Parameters:

col - the column

Returns:

the index (0 meaning first column)

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 interface: Index

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

Returns:

true if a rebuild is required.

canGetFirstOrLast

public boolean canGetFirstOrLast()

Description copied from interface: Index

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

Returns:

true if it can

findFirstOrLast

public Cursor findFirstOrLast(Session session,
                     boolean first)

Description copied from interface: Index

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)

getRowCountApproximation

public long getRowCountApproximation()

Description copied from interface: Index

Get the approximated row count for this table.

Returns:

the approximated row count

getPlanSQL

public String getPlanSQL()

Description copied from interface: Index

Get the message to show in a EXPLAIN statement.

Specified by:

getPlanSQL in interface Index

Overrides:

getPlanSQL in class BaseIndex

Returns:

the plan