Class MergeJoinResultSet

java.lang.Object

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

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

org.apache.derby.impl.sql.execute.JoinResultSet

org.apache.derby.impl.sql.execute.MergeJoinResultSet

All Implemented Interfaces:

CursorResultSet, NoPutResultSet, ResultSet, RowLocationRetRowSource, RowSource

class MergeJoinResultSet
extends JoinResultSet

Merge two result sets. The left result set (the outer result set) MUST be unique for this to work correctly.

Nested Class Summary

Nested classes/interfaces inherited from class BasicNoPutResultSetImpl

BasicNoPutResultSetImpl.FieldComparator

Field Summary

Fields

Modifier and Type	Field	Description
private static final int	EQUAL
private static final int	GREATER_THAN
private GeneratedMethod	leftGreaterThanRight
private static final int	LESS_THAN

Fields inherited from class JoinResultSet

isRightOpen, leftNumCols, leftResultSet, leftRow, mergedRow, notExistsRightSide, oneRowRightSide, restriction, restrictionTime, rightNumCols, rightResultSet, rightRow, rowsReturned, rowsSeenLeft, rowsSeenRight, userSuppliedOptimizerOverrides

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
MergeJoinResultSet(NoPutResultSet leftResultSet, int leftNumCols, NoPutResultSet rightResultSet, int rightNumCols, Activation activation, GeneratedMethod leftGreaterThanRight, GeneratedMethod restriction, int resultSetNumber, boolean oneRowRightSide, boolean notExistsRightSide, double optimizerEstimatedRowCount, double optimizerEstimatedCost)	Create a MergeJoinResultSet

Method Summary

Modifier and Type	Method	Description
void	close()	If the result set has been opened, close the open scan.
ExecRow	getNextRowCore()	Return the requested values computed from the next row (if any) for which the restriction evaluates to true.
private ExecRow	getReturnRow(ExecRow leftRow, ExecRow rightRow)	///////////////////////////////////////////////////////////////
long	getTimeSpent(int type)	Return the total amount of time spent in this ResultSet
private boolean	restrictionIsTrue()

Methods inherited from class JoinResultSet

clearScanState, closeRight, finish, getCurrentRow, getRowLocation, openCore, openRight, reopenCore

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, 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 Object

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

Methods inherited from interface ResultSet

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

Field Details

GREATER_THAN

private static final int GREATER_THAN

See Also:

• Constant Field Values

EQUAL

private static final int EQUAL

See Also:

• Constant Field Values

LESS_THAN

private static final int LESS_THAN

See Also:

• Constant Field Values

leftGreaterThanRight

private GeneratedMethod leftGreaterThanRight

Constructor Details

MergeJoinResultSet

MergeJoinResultSet(NoPutResultSet leftResultSet,
 int leftNumCols,
 NoPutResultSet rightResultSet,
 int rightNumCols,
 Activation activation,
 GeneratedMethod leftGreaterThanRight,
 GeneratedMethod restriction,
 int resultSetNumber,
 boolean oneRowRightSide,
 boolean notExistsRightSide,
 double optimizerEstimatedRowCount,
 double optimizerEstimatedCost)

Create a MergeJoinResultSet

Parameters:

leftResultSet - the left (outer) result set

leftNumCols - columns in left row

rightResultSet - the right (outer) result set

rightNumCols - columns in right row

activation - activation

leftGreaterThanRight - a generated method that is used to ascertain whether the row from the left result set is greater than the row from the right result set. returns 1,0,or -1 to indicate greater than, equal, or less than, respectively

restriction - generated method for additional qualification

resultSetNumber - the result set number

oneRowRightSide - ignored

optimizerEstimatedRowCount - self-explanatory

optimizerEstimatedCost - self-explanatory

Method Details

getNextRowCore

public ExecRow getNextRowCore()
                       throws StandardException

Return the requested values computed from the next row (if any) for which the restriction evaluates to true.

restriction parameters are evaluated for each row.

Specified by:

getNextRowCore in interface NoPutResultSet

Specified by:

getNextRowCore in class BasicNoPutResultSetImpl

Returns:

the next row in the join result

Throws:

StandardException - Thrown on error

StandardException - ResultSetNotOpen thrown if closed

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 JoinResultSet

Throws:

StandardException - thrown on error

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).

getReturnRow

private ExecRow getReturnRow(ExecRow leftRow,
 ExecRow rightRow)
                      throws StandardException

///////////////////////////////////////////////////////////////

Throws:

StandardException

restrictionIsTrue

private boolean restrictionIsTrue()
                           throws StandardException

Throws:

StandardException