Class LastIndexKeyResultSet

java.lang.Object

org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl

org.apache.derby.impl.sql.execute.NoPutResultSetImpl

org.apache.derby.impl.sql.execute.ScanResultSet

org.apache.derby.impl.sql.execute.LastIndexKeyResultSet

All Implemented Interfaces:

NoPutResultSet, ResultSet, RowLocationRetRowSource, RowSource

class LastIndexKeyResultSet
extends ScanResultSet

Return the last key in an index. Used to perform max().

Nested Class Summary

Nested classes/interfaces inherited from class BasicNoPutResultSetImpl

BasicNoPutResultSetImpl.FieldComparator

Field Summary

Fields

Modifier and Type	Field	Description
boolean	coarserLock
protected long	conglomId
protected Qualifier[][]	qualifiers
boolean	returnedRow
protected boolean	runTimeStatisticsOn
protected int	startSearchOperator
String	stopPositionString
protected int	stopSearchOperator
String	userSuppliedOptimizerOverrides

Fields inherited from class ScanResultSet

accessedCols, candidate, fetchRowLocations, indexName, isolationLevel, lockMode, resultRowBuilder, tableName

Fields inherited from class NoPutResultSetImpl

checkNullCols, clonedExecRow, cncLen, resultSetNumber, targetResultSet

Fields inherited from class BasicNoPutResultSetImpl

activation, beginTime, closeTime, compactRow, constructorTime, currentRow, endExecutionTime, finished, isOpen, isTopResultSet, nextTime, numOpens, openTime, optimizerEstimatedCost, optimizerEstimatedRowCount, resultDescription, rowsFiltered, rowsSeen, startExecutionTime, subqueryTrackingArray

Fields inherited from interface NoPutResultSet

ABSOLUTE, FIRST, LAST, NEXT, PREVIOUS, RELATIVE, TEMPORARY_RESULT_SET_NUMBER

Fields inherited from interface ResultSet

CURRENT_RESULTSET_ONLY, ENTIRE_RESULTSET_TREE, ISAFTERLAST, ISBEFOREFIRST, ISFIRST, ISLAST

Constructor Summary

Constructors

Constructor	Description
LastIndexKeyResultSet(Activation activation, int resultSetNumber, int resultRowTemplate, long conglomId, String tableName, String userSuppliedOptimizerOverrides, String indexName, int colRefItem, int lockMode, boolean tableLocked, int isolationLevel, double optimizerEstimatedRowCount, double optimizerEstimatedCost)	A last index key result set returns the last row from the index in question.

Method Summary

Modifier and Type	Method	Description
(package private) boolean	canGetInstantaneousLocks()	Can we get instantaneous locks when getting share row locks at READ COMMITTED.
void	close()	If the result set has been opened, close the open scan.
ExecRow	getCurrentRow()	This result set has its row from the last fetch done.
ExecRow	getNextRowCore()	Return the next row (if any) from the scan (if open).
long	getTimeSpent(int type)	Return the total amount of time spent in this ResultSet
void	openCore()	open a scan on the table. scan parameters are evaluated at each open, so there is probably some way of altering their values...

Methods inherited from class ScanResultSet

getScanIsolationLevel, initIsolationLevel, setRowLocationsState, toXML

Methods inherited from class NoPutResultSetImpl

clearCurrentRow, clearOrderableCache, closeRowSource, getCursorName, getNextRowFromRowSource, getResultDescription, getValidColumns, isForUpdate, markRowAsDeleted, needsRowLocation, needsRowLocationForDeferredCheckConstraints, needsToClone, offendingRowLocation, positionScanAtRowLocation, printQualifiers, resultSetNumber, rowLocation, setCurrentRow, setHasDeferrableChecks, setNeedsRowLocation, setTargetResultSet, skipRow, skipScan, unpackHashValue, updateRow

Methods inherited from class BasicNoPutResultSetImpl

addWarning, attachStatementContext, checkCancellationFlag, checkRowPosition, childrenToXML, cleanUp, dumpTimeStats, finish, finishAndRTS, getAbsoluteRow, getActivation, getAutoGeneratedKeysResultset, getBeginExecutionTimestamp, getCompactRow, getCurrentTimeMillis, getElapsedMillis, getEndExecutionTimestamp, getEstimatedRowCount, getExecuteTime, getExecutionFactory, getFirstRow, getLanguageConnectionContext, getLastRow, getNextRow, getPointOfAttachment, getPreviousRow, getRelativeRow, getRowNumber, getSubqueryTrackingArray, getTransactionController, getWarnings, isClosed, isXplainOnlyMode, markAsTopResultSet, modifiedRowCount, open, recordConstructorTime, reopenCore, requiresRelocking, returnsRows, setAfterLastRow, setBeforeFirstRow, setCompactRow, setCompatRow, toXML

Methods inherited from class Object

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

Field Details

conglomId

protected long conglomId

startSearchOperator

protected int startSearchOperator

stopSearchOperator

protected int stopSearchOperator

qualifiers

protected Qualifier[][] qualifiers

userSuppliedOptimizerOverrides

public String userSuppliedOptimizerOverrides

runTimeStatisticsOn

protected boolean runTimeStatisticsOn

stopPositionString

public String stopPositionString

coarserLock

public boolean coarserLock

returnedRow

public boolean returnedRow

Constructor Details

LastIndexKeyResultSet

public LastIndexKeyResultSet(Activation activation,
 int resultSetNumber,
 int resultRowTemplate,
 long conglomId,
 String tableName,
 String userSuppliedOptimizerOverrides,
 String indexName,
 int colRefItem,
 int lockMode,
 boolean tableLocked,
 int isolationLevel,
 double optimizerEstimatedRowCount,
 double optimizerEstimatedCost)
                      throws StandardException

A last index key result set returns the last row from the index in question. It is used as an ajunct to max().

Parameters:

activation - the activation for this result set, which provides the context for the row allocation operation.

resultSetNumber - The resultSetNumber for the ResultSet

resultRowTemplate - The saved item for result row template

conglomId - the conglomerate of the table to be scanned.

tableName - The full name of the table

userSuppliedOptimizerOverrides - Overrides specified by the user on the sql

indexName - The name of the index, if one used to access table.

colRefItem - An saved item for a bitSet of columns that are referenced in the underlying table. -1 if no item.

lockMode - The lock granularity to use (see TransactionController in access)

tableLocked - Whether or not the table is marked as using table locking (in sys.systables)

isolationLevel - Isolation level (specified or not) to use on scans

optimizerEstimatedRowCount - Estimated total # of rows by optimizer

optimizerEstimatedCost - Estimated total cost by optimizer

Throws:

StandardException - thrown when unable to create the result set

Method Details

canGetInstantaneousLocks

boolean canGetInstantaneousLocks()

Can we get instantaneous locks when getting share row locks at READ COMMITTED.

Specified by:

canGetInstantaneousLocks in class ScanResultSet

openCore

public void openCore()
              throws StandardException

open a scan on the table. scan parameters are evaluated at each open, so there is probably some way of altering their values...

Throws:

StandardException - thrown on failure to open

getNextRowCore

public ExecRow getNextRowCore()
                       throws StandardException

Return the next row (if any) from the scan (if open).

Specified by:

getNextRowCore in interface NoPutResultSet

Specified by:

getNextRowCore in class BasicNoPutResultSetImpl

Returns:

the next row in the result

Throws:

StandardException - thrown on failure to get next row

See Also:

• NoPutResultSet.getNextRowCore()

close

public void close()
           throws StandardException

If the result set has been opened, close the open scan.

Specified by:

close in interface ResultSet

Overrides:

close in class ScanResultSet

Throws:

StandardException - thrown on failure to close

getTimeSpent

public long getTimeSpent(int type)

Return the total amount of time spent in this ResultSet

Parameters:

type - CURRENT_RESULTSET_ONLY - time spent only in this ResultSet ENTIRE_RESULTSET_TREE - time spent in this ResultSet and below.

Returns:

long The total amount of time spent (in milliseconds).

getCurrentRow

public ExecRow getCurrentRow()
                      throws StandardException

This result set has its row from the last fetch done. If the cursor is closed, a null is returned.

Returns:

the last row returned;

Throws:

StandardException - thrown on failure.

See Also:

• CursorResultSet