Package org.apache.derby.impl.sql.execute

Class RowCountResultSet

java.lang.Object

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

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

org.apache.derby.impl.sql.execute.RowCountResultSet

All Implemented Interfaces:

CursorResultSet, NoPutResultSet, ResultSet, RowLocationRetRowSource, RowSource

class RowCountResultSet
extends NoPutResultSetImpl
implements CursorResultSet

This result set implements the filtering of rows needed for the and the . It sits on top of the normal SELECT's top result set, but under any ScrollInsensitiveResultSet needed for cursors. The latter positioning is needed for the correct functioning of and in the presence of scrollable and/or updatable result sets and CURRENT OF cursors. It is only ever generated if at least one of the two clauses is present.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl

BasicNoPutResultSetImpl.FieldComparator

Field Summary

Fields

Modifier and Type	Field	Description
private long	fetchFirst
private GeneratedMethod	fetchFirstMethod
private boolean	hasJDBClimitClause
private long	offset
private GeneratedMethod	offsetMethod
private long	rowsFetched	Holds the number of rows returned so far in this round of using the result set.
private boolean	runTimeStatsOn
(package private) NoPutResultSet	source
private boolean	virginal	True if we haven't yet fetched any rows from this result set.

Fields inherited from class org.apache.derby.impl.sql.execute.NoPutResultSetImpl

checkNullCols, clonedExecRow, cncLen, resultSetNumber, targetResultSet

Fields inherited from class org.apache.derby.impl.sql.execute.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 org.apache.derby.iapi.sql.execute.NoPutResultSet

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

Fields inherited from interface org.apache.derby.iapi.sql.ResultSet

CURRENT_RESULTSET_ONLY, ENTIRE_RESULTSET_TREE, ISAFTERLAST, ISBEFOREFIRST, ISFIRST, ISLAST

Constructor Summary

Constructors

Constructor	Description
RowCountResultSet(NoPutResultSet s, Activation a, int resultSetNumber, GeneratedMethod offsetMethod, GeneratedMethod fetchFirstMethod, boolean hasJDBClimitClause, double optimizerEstimatedRowCount, double optimizerEstimatedCost)	RowCountResultSet constructor

Method Summary

Modifier and Type	Method	Description
void	clearCurrentRow()	Clear the current row
void	close()	Close needs to invalidate any dependent statements, if this is a cursor.
void	finish()	Tells the system that there will be no more access to any database information via this result set; in particular, no more calls to open().
ExecRow	getCurrentRow()	Gets information from source
ExecRow	getNextRowCore()	Return the requested values computed from the next row (if any)
RowLocation	getRowLocation()	Gets information from its source.
long	getTimeSpent(int type)	Return the total amount of time spent in this ResultSet
ProjectRestrictResultSet	getUnderlyingProjectRestrictRS()	Return underlying result set (the source og this result set) if it is a ProjectRestrictResultSet, else null.
boolean	isForUpdate()	Override of NoPutResultSetImpl method.
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...
void	reopenCore()	Reopen 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 org.apache.derby.impl.sql.execute.NoPutResultSetImpl

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

Methods inherited from class org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl

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

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.derby.iapi.sql.ResultSet

addWarning, checkRowPosition, cleanUp, getAbsoluteRow, getActivation, getAutoGeneratedKeysResultset, getBeginExecutionTimestamp, getCursorName, getEndExecutionTimestamp, getExecuteTime, getFirstRow, getLastRow, getNextRow, getPreviousRow, getRelativeRow, getResultDescription, getRowNumber, getSubqueryTrackingArray, getWarnings, isClosed, modifiedRowCount, open, returnsRows, setAfterLastRow, setBeforeFirstRow, toXML

Field Detail

source

final NoPutResultSet source

runTimeStatsOn

private final boolean runTimeStatsOn

offset

private long offset

fetchFirst

private long fetchFirst

offsetMethod

private final GeneratedMethod offsetMethod

fetchFirstMethod

private final GeneratedMethod fetchFirstMethod

hasJDBClimitClause

private final boolean hasJDBClimitClause

virginal

private boolean virginal

True if we haven't yet fetched any rows from this result set. Will be reset on close so the result set is ready to reuse.

rowsFetched

private long rowsFetched

Holds the number of rows returned so far in this round of using the result set. Will be reset on close so the result set is ready to reuse.

Constructor Detail

RowCountResultSet

RowCountResultSet(NoPutResultSet s,
                  Activation a,
                  int resultSetNumber,
                  GeneratedMethod offsetMethod,
                  GeneratedMethod fetchFirstMethod,
                  boolean hasJDBClimitClause,
                  double optimizerEstimatedRowCount,
                  double optimizerEstimatedCost)
           throws StandardException

RowCountResultSet constructor

Parameters:

s - The source result set being filtered

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

resultSetNumber - The resultSetNumber for the ResultSet

offsetMethod - Generated method

fetchFirstMethod - Generated method

hasJDBClimitClause - True if offset/fetchFirst clauses were added by JDBC LIMIT escape syntax

optimizerEstimatedRowCount - Estimated total # of rows by optimizer

optimizerEstimatedCost - Estimated total cost by optimizer

Throws:

StandardException - Standard error policy

Method Detail

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...

Specified by:

openCore in interface NoPutResultSet

Throws:

StandardException - thrown if cursor finished.

reopenCore

public void reopenCore()
                throws StandardException

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

Specified by:

reopenCore in interface NoPutResultSet

Overrides:

reopenCore in class BasicNoPutResultSetImpl

Throws:

StandardException - thrown if cursor finished.

See Also:

NoPutResultSet.openCore()

getNextRowCore

public ExecRow getNextRowCore()
                       throws StandardException

Return the requested values computed from the next row (if any)

Specified by:

getNextRowCore in interface NoPutResultSet

Specified by:

getNextRowCore in class BasicNoPutResultSetImpl

Returns:

the next row in the result

Throws:

StandardException - thrown on failure.

StandardException - ResultSetNotOpen thrown if not yet open.

See Also:

NoPutResultSet.getNextRowCore()

getTimeSpent

public long getTimeSpent(int type)

Return the total amount of time spent in this ResultSet

Specified by:

getTimeSpent in interface 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).

close

public void close()
           throws StandardException

Description copied from class: NoPutResultSetImpl

Close needs to invalidate any dependent statements, if this is a cursor. Must be called by any subclasses that override close().

Specified by:

close in interface ResultSet

Overrides:

close in class NoPutResultSetImpl

Throws:

StandardException - on error

See Also:

ResultSet.close()

finish

public void finish()
            throws StandardException

Description copied from interface: ResultSet

Tells the system that there will be no more access to any database information via this result set; in particular, no more calls to open(). Will close the result set if it is not already closed.

Specified by:

finish in interface ResultSet

Overrides:

finish in class BasicNoPutResultSetImpl

Throws:

StandardException - on error

See Also:

ResultSet.finish()

clearCurrentRow

public final void clearCurrentRow()

Description copied from class: NoPutResultSetImpl

Clear the current row

Specified by:

clearCurrentRow in interface ResultSet

Overrides:

clearCurrentRow in class NoPutResultSetImpl

See Also:

ResultSet.clearCurrentRow()

getRowLocation

public RowLocation getRowLocation()
                           throws StandardException

Gets information from its source.

Specified by:

getRowLocation in interface CursorResultSet

Returns:

the row location of the current cursor row.

Throws:

StandardException - thrown on failure to get location from storage engine

See Also:

CursorResultSet.getRowLocation()

getCurrentRow

public ExecRow getCurrentRow()
                      throws StandardException

Gets information from source

Specified by:

getCurrentRow in interface CursorResultSet

Returns:

the last row returned.

Throws:

StandardException - thrown on failure.

See Also:

CursorResultSet.getCurrentRow()

isForUpdate

public boolean isForUpdate()

Override of NoPutResultSetImpl method. Ask the source.

Specified by:

isForUpdate in interface NoPutResultSet

Overrides:

isForUpdate in class NoPutResultSetImpl

Returns:

Whether or not the result set is for update.

getUnderlyingProjectRestrictRS

public ProjectRestrictResultSet getUnderlyingProjectRestrictRS()

Return underlying result set (the source og this result set) if it is a ProjectRestrictResultSet, else null.