RowCountResultSet (Apache Derby V10.14 Internals)

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.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 class org.apache.derby.impl.sql.execute.NoPutResultSetImpl
checkNullCols, clonedExecRow, cncLen, resultSetNumber, targetResultSet

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

All Methods Instance Methods Concrete Methods
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.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 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 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.

Class RowCountResultSet

Nested Class Summary

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

Field Summary

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

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

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

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

Constructor Summary

Method Summary

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

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

Methods inherited from class java.lang.Object

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

Field Detail

source

runTimeStatsOn

offset

fetchFirst

offsetMethod

fetchFirstMethod

hasJDBClimitClause

virginal

rowsFetched

Constructor Detail

RowCountResultSet

Method Detail

openCore

reopenCore

getNextRowCore

getTimeSpent

close

finish

clearCurrentRow

getRowLocation

getCurrentRow

isForUpdate

getUnderlyingProjectRestrictRS