TableScanResultSet (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.ScanResultSet
    - - org.apache.derby.impl.sql.execute.TableScanResultSet

All Implemented Interfaces:

java.lang.Cloneable, CursorResultSet, NoPutResultSet, ResultSet, RowLocationRetRowSource, RowSource

Direct Known Subclasses:

BulkTableScanResultSet, MultiProbeTableScanResultSet, ValidateCheckConstraintResultSet
```
class TableScanResultSet
extends ScanResultSet
implements CursorResultSet, java.lang.Cloneable
```
Takes a table and a table filter and returns the table's rows satisfying the filter as a result set. There are several things we could do during object construction that are done in the open and next calls, to improve performance.

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
`boolean`	`coarserLock`
`protected long`	`conglomId`
`protected boolean`	`currentRowIsValid`
`protected DynamicCompiledOpenConglomInfo`	`dcoci`
`private long`	`estimatedRowCount`
`protected boolean`	`firstScan`
`boolean`	`forUpdate`
`protected int[]`	`indexCols`
`boolean`	`isConstraint`
`protected boolean`	`isKeyed`
`protected boolean`	`nextDone`
`boolean`	`oneRowScan`
`protected BackingStoreHashtable`	`past2FutureTbl`	This field is used by beetle 3865, updateable cursor using index.
`Qualifier[][]`	`qualifiers`
`protected boolean`	`qualify`
`private RowLocation`	`rlTemplate`
`int`	`rowsPerRead`
`protected long`	`rowsThisScan`
`protected boolean`	`runTimeStatisticsOn`
`(package private) boolean`	`sameStartStopPosition`
`protected ScanController`	`scanController`
`protected boolean`	`scanControllerOpened`
`private java.util.Properties`	`scanProperties`
`protected boolean`	`scanRepositioned`
`protected StaticCompiledOpenConglomInfo`	`scoci`
`protected GeneratedMethod`	`startKeyGetter`
`protected ExecIndexRow`	`startPosition`
`java.lang.String`	`startPositionString`
`protected int`	`startSearchOperator`
`protected GeneratedMethod`	`stopKeyGetter`
`protected ExecIndexRow`	`stopPosition`
`java.lang.String`	`stopPositionString`
`protected int`	`stopSearchOperator`
`java.lang.String`	`userSuppliedOptimizerOverrides`

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

Fields inherited from class org.apache.derby.impl.sql.execute.ScanResultSet
accessedCols, candidate, fetchRowLocations, indexName, isolationLevel, lockMode, resultRowBuilder, tableName

Constructor Summary

Constructors
Constructor	Description
TableScanResultSet(long conglomId, StaticCompiledOpenConglomInfo scoci, Activation activation, int resultRowTemplate, int resultSetNumber, GeneratedMethod startKeyGetter, int startSearchOperator, GeneratedMethod stopKeyGetter, int stopSearchOperator, boolean sameStartStopPosition, Qualifier[][] qualifiers, java.lang.String tableName, java.lang.String userSuppliedOptimizerOverrides, java.lang.String indexName, boolean isConstraint, boolean forUpdate, int colRefItem, int indexColItem, int lockMode, boolean tableLocked, int isolationLevel, int rowsPerRead, boolean oneRowScan, double optimizerEstimatedRowCount, double optimizerEstimatedCost)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected boolean`	`canGetInstantaneousLocks()`	Can we get instantaneous locks when getting share row locks at READ COMMITTED.
`java.lang.Object`	`clone()`	Shallow clone this result set.
`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).
`RowLocation`	`getRowLocation()`	This result set has its row location from the last fetch done.
`java.util.Properties`	`getScanProperties()`
`long`	`getTimeSpent(int type)`	Return the total amount of time spent in this ResultSet
`(package private) void`	`initStartAndStopKey()`	Initialize the `startPosition` and `stopPosition` fields which are used to limit the rows returned by the scan.
`boolean`	`isForUpdate()`	Is this ResultSet or it's source result set for update
`(package private) boolean`	`loopControl(boolean moreRows)`
`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...
`protected void`	`openScanController(TransactionController tc)`
`void`	`positionScanAtRowLocation(RowLocation rl)`	Positions the cursor in the specified rowLocation.
`private java.lang.String`	`printPosition(int searchOperator, GeneratedMethod positionGetter, ExecIndexRow positioner)`	Return a start or stop positioner as a String.
`java.lang.String`	`printStartPosition()`	Print an array of Qualifiers to the trace stream.
`java.lang.String`	`printStopPosition()`
`void`	`reopenCore()`	Reopen a table scan.
`protected void`	`reopenScanController()`
`boolean`	`requiresRelocking()`	Do we need to relock the row when going to the heap.
`protected void`	`setRowCountIfPossible(long rowsThisScan)`	Update the number of rows in the scan controller.

Methods inherited from class org.apache.derby.impl.sql.execute.NoPutResultSetImpl
clearCurrentRow, clearOrderableCache, closeRowSource, getCursorName, getNextRowFromRowSource, getResultDescription, getValidColumns, markRowAsDeleted, needsRowLocation, needsRowLocationForDeferredCheckConstraints, needsToClone, offendingRowLocation, printQualifiers, resultSetNumber, rowLocation, setCurrentRow, setHasDeferrableChecks, setNeedsRowLocation, setTargetResultSet, skipRow, skipScan, unpackHashValue, updateRow

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.apache.derby.iapi.sql.ResultSet
addWarning, checkRowPosition, cleanUp, clearCurrentRow, finish, getAbsoluteRow, getActivation, getAutoGeneratedKeysResultset, getBeginExecutionTimestamp, getCursorName, getEndExecutionTimestamp, getExecuteTime, getFirstRow, getLastRow, getNextRow, getPreviousRow, getRelativeRow, getResultDescription, getRowNumber, getSubqueryTrackingArray, getWarnings, isClosed, modifiedRowCount, open, returnsRows, setAfterLastRow, setBeforeFirstRow, toXML

Methods inherited from class org.apache.derby.impl.sql.execute.ScanResultSet
getScanIsolationLevel, initIsolationLevel, setRowLocationsState, toXML

- Field Detail
  - scanController
```
protected ScanController scanController
```
  - scanControllerOpened
```
protected boolean scanControllerOpened
```
  - isKeyed
```
protected boolean isKeyed
```
  - firstScan
```
protected boolean firstScan
```
  - startPosition
```
protected ExecIndexRow startPosition
```
  - stopPosition
```
protected ExecIndexRow stopPosition
```
  - conglomId
```
protected long conglomId
```
  - dcoci
```
protected DynamicCompiledOpenConglomInfo dcoci
```
  - scoci
```
protected StaticCompiledOpenConglomInfo scoci
```
  - startKeyGetter
```
protected GeneratedMethod startKeyGetter
```
  - startSearchOperator
```
protected int startSearchOperator
```
  - stopKeyGetter
```
protected GeneratedMethod stopKeyGetter
```
  - stopSearchOperator
```
protected int stopSearchOperator
```
  - qualifiers
```
public Qualifier[][] qualifiers
```
  - userSuppliedOptimizerOverrides
```
public java.lang.String userSuppliedOptimizerOverrides
```
  - runTimeStatisticsOn
```
protected boolean runTimeStatisticsOn
```
  - indexCols
```
protected int[] indexCols
```
  - rowsPerRead
```
public int rowsPerRead
```
  - forUpdate
```
public boolean forUpdate
```
  - sameStartStopPosition
```
final boolean sameStartStopPosition
```
  - nextDone
```
protected boolean nextDone
```
  - rlTemplate
```
private RowLocation rlTemplate
```
  - scanProperties
```
private java.util.Properties scanProperties
```
  - startPositionString
```
public java.lang.String startPositionString
```
  - stopPositionString
```
public java.lang.String stopPositionString
```
  - isConstraint
```
public boolean isConstraint
```
  - coarserLock
```
public boolean coarserLock
```
  - oneRowScan
```
public boolean oneRowScan
```
  - rowsThisScan
```
protected long rowsThisScan
```
  - estimatedRowCount
```
private long estimatedRowCount
```
  - past2FutureTbl
```
protected BackingStoreHashtable past2FutureTbl
```
    This field is used by beetle 3865, updateable cursor using index. It is a hash table containing updated rows that are thrown into future direction of the index scan, and as a result we'll hit it again but should skip it. The hash table will spill to disk if it grows too big to be kept in memory.
  - qualify
```
protected boolean qualify
```
  - currentRowIsValid
```
protected boolean currentRowIsValid
```
  - scanRepositioned
```
protected boolean scanRepositioned
```
- Constructor Detail
  - TableScanResultSet
```
TableScanResultSet(long conglomId,
                   StaticCompiledOpenConglomInfo scoci,
                   Activation activation,
                   int resultRowTemplate,
                   int resultSetNumber,
                   GeneratedMethod startKeyGetter,
                   int startSearchOperator,
                   GeneratedMethod stopKeyGetter,
                   int stopSearchOperator,
                   boolean sameStartStopPosition,
                   Qualifier[][] qualifiers,
                   java.lang.String tableName,
                   java.lang.String userSuppliedOptimizerOverrides,
                   java.lang.String indexName,
                   boolean isConstraint,
                   boolean forUpdate,
                   int colRefItem,
                   int indexColItem,
                   int lockMode,
                   boolean tableLocked,
                   int isolationLevel,
                   int rowsPerRead,
                   boolean oneRowScan,
                   double optimizerEstimatedRowCount,
                   double optimizerEstimatedCost)
            throws StandardException
```
    Throws:
    
    StandardException
- 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 on failure to open
  - initStartAndStopKey
```
void initStartAndStopKey()
                  throws StandardException
```
    Initialize the startPosition and stopPosition fields which are used to limit the rows returned by the scan.
    
    Throws:
    
    StandardException
  - openScanController
```
protected void openScanController(TransactionController tc)
                           throws StandardException
```
    Throws:
    
    StandardException
  - reopenScanController
```
protected void reopenScanController()
                             throws StandardException
```
    Throws:
    
    StandardException
  - reopenCore
```
public void reopenCore()
                throws StandardException
```
    Reopen a table scan. Here we take advantage of the reopenScan() interface on scanController for optimimal performance on joins where we are an inner table.
    
    Specified by:
    
    reopenCore in interface NoPutResultSet
    
    Overrides:
    
    reopenCore in class BasicNoPutResultSetImpl
    
    Throws:
    
    StandardException - thrown on failure to open
    
    See Also:
    
    NoPutResultSet.openCore()
  - loopControl
```
boolean loopControl(boolean moreRows)
             throws StandardException
```
    Throws:
    
    StandardException
  - 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 - 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
```
    This result set has its row location from the last fetch done. If the cursor is closed, or the row has been deleted a null is returned.
    
    Specified by:
    
    getRowLocation in interface CursorResultSet
    
    Returns:
    
    the row location of the current cursor row.
    
    Throws:
    
    StandardException - thrown on failure to get row location
    
    See Also:
    
    CursorResultSet
  - getCurrentRow
```
public ExecRow getCurrentRow()
                      throws StandardException
```
    This result set has its row from the last fetch done. If the cursor is closed, the row has been deleted, or no longer qualifies (for forward only result sets) a null is returned.
    
    Specified by:
    
    getCurrentRow in interface CursorResultSet
    
    Returns:
    
    the last row returned;
    
    Throws:
    
    StandardException - thrown on failure.
    
    See Also:
    
    CursorResultSet
  - positionScanAtRowLocation
```
public void positionScanAtRowLocation(RowLocation rl)
                               throws StandardException
```
    Description copied from interface: NoPutResultSet
    
    Positions the cursor in the specified rowLocation. Used for scrollable insensitive result sets in order to position the cursor back to a row that has already be visited.
    
    Specified by:
    
    positionScanAtRowLocation in interface NoPutResultSet
    
    Overrides:
    
    positionScanAtRowLocation in class NoPutResultSetImpl
    
    Parameters:
    
    rl - row location of the current cursor row
    
    Throws:
    
    StandardException - thrown on failure to get location from storage engine
    
    See Also:
    
    Also sets qualify to false so that later calls to getCurrentRow will not attempt to re-qualify the current row.
  - printStartPosition
```
public java.lang.String printStartPosition()
```
    Print an array of Qualifiers to the trace stream.
  - printStopPosition
```
public java.lang.String printStopPosition()
```
  - printPosition
```
private java.lang.String printPosition(int searchOperator,
                                       GeneratedMethod positionGetter,
                                       ExecIndexRow positioner)
```
    Return a start or stop positioner as a String. If we already generated the information, then use that. Otherwise, invoke the activation to get it.
  - getScanProperties
```
public java.util.Properties getScanProperties()
```
  - requiresRelocking
```
public boolean requiresRelocking()
```
    Description copied from interface: NoPutResultSet
    
    Do we need to relock the row when going to the heap.
    
    Specified by:
    
    requiresRelocking in interface NoPutResultSet
    
    Overrides:
    
    requiresRelocking in class BasicNoPutResultSetImpl
    
    Returns:
    
    Whether or not we need to relock the row when going to the heap.
    
    See Also:
    
    NoPutResultSet.requiresRelocking()
  - setRowCountIfPossible
```
protected final void setRowCountIfPossible(long rowsThisScan)
                                    throws StandardException
```
    Update the number of rows in the scan controller. NOTE: It would be more efficient to only update the scan controller if the optimizer's estimated number of rows were wrong by more than some threshold (like 10%). This would require a little more work than I have the time for now, however, as the row estimate that is given to this result set is the total number of rows for all scans, not the number of rows per scan.
    
    Parameters:
    
    rowsThisScan - The number of rows to update the scanController to
    
    Throws:
    
    StandardException - Thrown on error
  - canGetInstantaneousLocks
```
protected boolean canGetInstantaneousLocks()
```
    Can we get instantaneous locks when getting share row locks at READ COMMITTED.
    
    Specified by:
    
    canGetInstantaneousLocks in class ScanResultSet
  - isForUpdate
```
public boolean isForUpdate()
```
    Is this ResultSet or it's source result set for update
    
    Specified by:
    
    isForUpdate in interface NoPutResultSet
    
    Overrides:
    
    isForUpdate in class NoPutResultSetImpl
    
    Returns:
    
    Whether or not the result set is for update.
  - clone
```
public java.lang.Object clone()
```
    Shallow clone this result set. Used in trigger reference. beetle 4373.
    
    Overrides:
    
    clone in class java.lang.Object

Class TableScanResultSet

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

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

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

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

Field Detail

scanController

scanControllerOpened

isKeyed

firstScan

startPosition

stopPosition

conglomId

dcoci

scoci

startKeyGetter

startSearchOperator

stopKeyGetter

stopSearchOperator

qualifiers

userSuppliedOptimizerOverrides

runTimeStatisticsOn

indexCols

rowsPerRead

forUpdate

sameStartStopPosition

nextDone

rlTemplate

scanProperties

startPositionString

stopPositionString

isConstraint

coarserLock

oneRowScan

rowsThisScan

estimatedRowCount

past2FutureTbl

qualify

currentRowIsValid

scanRepositioned

Constructor Detail

TableScanResultSet

Method Detail

openCore

initStartAndStopKey

openScanController

reopenScanController

reopenCore

loopControl

getNextRowCore

close

getTimeSpent

getRowLocation

getCurrentRow

positionScanAtRowLocation

printStartPosition

printStopPosition

printPosition

getScanProperties

requiresRelocking

setRowCountIfPossible

canGetInstantaneousLocks

isForUpdate

clone