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

ScanIndex(RegularTable table, int id, 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.
void	commit(int operation, Row row) Commit the operation for a row.
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.
int	getColumnIndex(Column col) Get the index of a column in the list of index columns
double	getCost(Session session, int[] masks) Calculate the cost to find rows.
java.lang.String	getCreateSQL() Build a SQL statement to re-create this object.
java.lang.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 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, compareKeys, compareRows, containsNullAndAllowMultipleNull, findNext, getColumnListSQL, getColumns, getCostRangeIndex, getCreateSQLForCopy, getDropSQL, getDuplicateKeyException, getIndexColumns, getIndexType, getLookupCost, getRootPageId, 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

Constructor Detail

ScanIndex

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

Method Detail

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

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

getCreateSQL

public java.lang.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 class: BaseIndex

Close this index.

Specified by:

close in interface Index

Specified by:

close in class BaseIndex

Parameters:

session - the session

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 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

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 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

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

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 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)

getRowCountApproximation

public long getRowCountApproximation()

Description copied from interface: Index

Get the approximated row count for this table.

Returns:

the approximated row count

getPlanSQL

public java.lang.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