org.apache.derby.impl.sql.execute

Class UnionResultSet

java.lang.Object

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

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

org.apache.derby.impl.sql.execute.UnionResultSet

All Implemented Interfaces:

CursorResultSet, NoPutResultSet, ResultSet, RowLocationRetRowSource, RowSource

class UnionResultSet
extends NoPutResultSetImpl
implements CursorResultSet

Takes two result sets and returns their union (all). (Any duplicate elimination is performed above this ResultSet.)

Field Summary

Fields

Modifier and Type	Field and Description
int	rowsReturned
int	rowsSeenLeft
int	rowsSeenRight
NoPutResultSet	source1
private int	source1FinalRowCount
NoPutResultSet	source2
private int	whichSource

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.ResultSet

CURRENT_RESULTSET_ONLY, ENTIRE_RESULTSET_TREE, ISAFTERLAST, ISBEFOREFIRST, ISFIRST, ISLAST

Fields inherited from interface org.apache.derby.iapi.sql.execute.NoPutResultSet

ABSOLUTE, FIRST, LAST, NEXT, PREVIOUS, RELATIVE

Constructor Summary

Constructors

Constructor and Description
UnionResultSet(NoPutResultSet source1, NoPutResultSet source2, Activation activation, int resultSetNumber, double optimizerEstimatedRowCount, double optimizerEstimatedCost)

Method Summary

Modifier and Type	Method and Description
void	close() If the result set has been opened, close the currently open source.
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() A union has a single underlying row at a time, although from one of several sources.
ExecRow	getNextRowCore() If there are rows still on the first source, return the next one; otherwise, switch to the second source and return a row from there.
ResultDescription	getResultDescription() Returns the description of the first source.
RowLocation	getRowLocation() A union has a single underlying row at a time, although from one of several sources.
long	getTimeSpent(int type) Return the total amount of time spent in this ResultSet
void	openCore() open the first source.

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

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

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

addWarning, attachStatementContext, checkCancellationFlag, checkRowPosition, 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, reopenCore, requiresRelocking, returnsRows, setAfterLastRow, setBeforeFirstRow, setCompactRow, setCompatRow

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, clearCurrentRow, getAbsoluteRow, getActivation, getAutoGeneratedKeysResultset, getBeginExecutionTimestamp, getCursorName, getEndExecutionTimestamp, getExecuteTime, getFirstRow, getLastRow, getNextRow, getPreviousRow, getRelativeRow, getRowNumber, getSubqueryTrackingArray, getWarnings, isClosed, modifiedRowCount, open, returnsRows, setAfterLastRow, setBeforeFirstRow

Field Detail

rowsSeenLeft

public int rowsSeenLeft

rowsSeenRight

public int rowsSeenRight

rowsReturned

public int rowsReturned

whichSource

private int whichSource

source1FinalRowCount

private int source1FinalRowCount

source1

public NoPutResultSet source1

source2

public NoPutResultSet source2

Constructor Detail

UnionResultSet

public UnionResultSet(NoPutResultSet source1,
                      NoPutResultSet source2,
                      Activation activation,
                      int resultSetNumber,
                      double optimizerEstimatedRowCount,
                      double optimizerEstimatedCost)

Method Detail

getResultDescription

public ResultDescription getResultDescription()

Returns the description of the first source. Assumes the compiler ensured both sources had the same description.

Specified by:

getResultDescription in interface ResultSet

Overrides:

getResultDescription in class NoPutResultSetImpl

Returns:

A ResultDescription describing the results of the statement.

openCore

public void openCore()
              throws StandardException

open the first source.

Specified by:

openCore in interface NoPutResultSet

Throws:

StandardException - thrown on failure

getNextRowCore

public ExecRow getNextRowCore()
                       throws StandardException

If there are rows still on the first source, return the next one; otherwise, switch to the second source and return a row from there.

Specified by:

getNextRowCore in interface NoPutResultSet

Specified by:

getNextRowCore in class BasicNoPutResultSetImpl

Returns:

the next row in the result

Throws:

StandardException - thrown on failure

See Also:

NoPutResultSet.getNextRowCore()

close

public void close()
           throws StandardException

If the result set has been opened, close the currently open source.

Specified by:

close in interface ResultSet

Overrides:

close in class NoPutResultSetImpl

Throws:

StandardException - thrown on error

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

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).

getRowLocation

public RowLocation getRowLocation()
                           throws StandardException

A union has a single underlying row at a time, although from one of several sources.

Specified by:

getRowLocation in interface CursorResultSet

Returns:

the row location of the current cursor row.

Throws:

StandardException - thrown on failure

See Also:

CursorResultSet

getCurrentRow

public ExecRow getCurrentRow()
                      throws StandardException

A union has a single underlying row at a time, although from one of several sources.

Specified by:

getCurrentRow in interface CursorResultSet

Returns:

the current row.

Throws:

StandardException - thrown on failure.

See Also:

CursorResultSet