Package org.h2.index

Class DualIndex

java.lang.Object

org.h2.engine.DbObject

org.h2.schema.SchemaObject

org.h2.index.Index

org.h2.index.VirtualTableIndex

org.h2.index.DualIndex

All Implemented Interfaces:

HasSQL

public class DualIndex
extends VirtualTableIndex

An index for the DUAL table.

Field Summary

Fields inherited from class org.h2.index.Index

columnIds, columns, indexColumns, indexType, table, uniqueColumnColumn

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

Constructor	Description
DualIndex(DualTable table)

Method Summary

Modifier and Type	Method	Description
boolean	canGetFirstOrLast()	Check if the index can directly look up the lowest or highest value of a column.
Cursor	find(SessionLocal session, SearchRow first, SearchRow last, boolean reverse)	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.
double	getCost(SessionLocal session, int[] masks, TableFilter[] filters, int filter, SortOrder sortOrder, AllColumnsForPlan allColumnsSet, boolean isSelectCommand)	Estimate the cost to search for rows given the search mask.
String	getCreateSQL()	Construct the CREATE ...
String	getPlanSQL()	Get the message to show in a EXPLAIN statement.

Methods inherited from class org.h2.index.VirtualTableIndex

add, checkRename, close, getRowCount, getRowCountApproximation, needRebuild, remove, remove, truncate

Methods inherited from class org.h2.index.Index

canFindNext, canScan, checkIndexColumnTypes, compareRows, findNext, getColumnIndex, getColumns, getCostRangeIndex, getCreateSQLForCopy, getDiskSpaceUsed, getDuplicateKeyException, getDuplicatePrimaryKeyMessage, getIndexColumns, getIndexType, getRow, getRowFactory, getTable, getType, getUniqueColumnCount, getUniqueRowFactory, isFindUsingFullTableScan, isFirstColumn, isRowIdIndex, needsUniqueCheck, removeChildrenAndResources, update

Methods inherited from class org.h2.schema.SchemaObject

getSchema, getSQL, getSQL

Methods inherited from class org.h2.engine.DbObject

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

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.h2.util.HasSQL

getTraceSQL

Constructor Details

DualIndex

public DualIndex(DualTable table)

Method Details

find

public Cursor find(SessionLocal session,
 SearchRow first,
 SearchRow last,
 boolean reverse)

Description copied from class: Index

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

Specified by:

find in class Index

Parameters:

session - the session

first - the first row, or null for no limit

last - the last row, or null for no limit

reverse - if true, iterate in reverse (descending) order

Returns:

the cursor to iterate over the results

getCost

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

Description copied from class: 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.

Specified by:

getCost in class Index

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

isSelectCommand - is this for an SELECT command

Returns:

the estimated cost

getCreateSQL

public String getCreateSQL()

Description copied from class: DbObject

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

Overrides:

getCreateSQL in class Index

Returns:

the SQL statement

canGetFirstOrLast

public boolean canGetFirstOrLast()

Description copied from class: Index

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

Overrides:

canGetFirstOrLast in class Index

Returns:

true if it can

findFirstOrLast

public Cursor findFirstOrLast(SessionLocal session,
 boolean first)

Description copied from class: 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.

Overrides:

findFirstOrLast in class Index

Parameters:

session - the session

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

Returns:

a cursor (never null)

getPlanSQL

public String getPlanSQL()

Description copied from class: Index

Get the message to show in a EXPLAIN statement.

Overrides:

getPlanSQL in class Index

Returns:

the plan