Class ScanResultSet
java.lang.Object
org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl
org.apache.derby.impl.sql.execute.NoPutResultSetImpl
org.apache.derby.impl.sql.execute.ScanResultSet
- All Implemented Interfaces:
NoPutResultSet
,ResultSet
,RowLocationRetRowSource
,RowSource
- Direct Known Subclasses:
DependentResultSet
,HashScanResultSet
,LastIndexKeyResultSet
,TableScanResultSet
Abstract
Example: if accessedCols indicates that we want to retrieve columns 1 and 4, then candidate row will have space for 5 columns (because that's the size of the rows in the underlying object), but only cols "1" and "4" will have values:
Rows returned by this ScanResultSet will have the values:
ResultSet
class for NoPutResultSet
s which
contain a scan. Returns rows that may be a column sub-set of the
rows in the underlying object to be scanned. If accessedCols is
not null then a sub-set of columns will be fetched from the underlying
object (usually into the candidate row object), then the returned
rows will be a compacted form of that row, with the not-fetched columns
moved out. If accessedCols is null then the full row will be returned.
Example: if accessedCols indicates that we want to retrieve columns 1 and 4, then candidate row will have space for 5 columns (because that's the size of the rows in the underlying object), but only cols "1" and "4" will have values:
0 1 2 3 4 [ - , COL1, - , - , COL4 ]
Rows returned by this ScanResultSet will have the values:
0 1 [ COL1, COL4 ]
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl
BasicNoPutResultSetImpl.FieldComparator
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Field Summary
FieldsModifier and TypeFieldDescriptionprotected FormatableBitSet
If not null indicates the subset of columns that need to be pulled from the underlying object to be scanned.(package private) final ExecRow
The candidate row, matches the shape of the rows in the underlying object to be scanned.protected boolean
true if the scan should pick up row locations(package private) int
The scan isolation level.private boolean
Tells whether the isolation level needs to be updated.(package private) int
The actual lock mode used.(package private) final ExecRowBuilder
Object used to create and reset the candidate row.private final int
The lock mode supplied through the constructor.private final boolean
If true, the table is marked as table locked in SYS.SYSTABLES.private final boolean
If true, the isolation level is unspecified and must be refreshed on each open.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
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Constructor Summary
ConstructorsConstructorDescriptionScanResultSet
(Activation activation, int resultSetNumber, int resultRowTemplate, int lockMode, boolean tableLocked, int isolationLevel, int colRefItem, double optimizerEstimatedRowCount, double optimizerEstimatedCost) Construct aScanResultSet
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Method Summary
Modifier and TypeMethodDescription(package private) abstract boolean
Can we get instantaneous locks when getting share row locks at READ COMMITTED.void
close()
Close the result set.private int
getLockMode
(int languageLevel) Get the lock mode based on the language isolation level.int
Return the isolation level of the scan in the result set.(package private) void
Initialize the isolation level and the lock mode.protected void
Determine whether this scan should return row locationsProduce an xml image of this ResultSet and its descendant ResultSets.private int
translateLanguageIsolationLevel
(int languageLevel) Translate isolation level from language to store.Methods inherited from class org.apache.derby.impl.sql.execute.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 org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl
addWarning, attachStatementContext, checkCancellationFlag, checkRowPosition, childrenToXML, cleanUp, dumpTimeStats, finish, finishAndRTS, getAbsoluteRow, getActivation, getAutoGeneratedKeysResultset, getBeginExecutionTimestamp, getCompactRow, getCurrentTimeMillis, getElapsedMillis, getEndExecutionTimestamp, getEstimatedRowCount, getExecuteTime, getExecutionFactory, getFirstRow, getLanguageConnectionContext, getLastRow, getNextRow, getNextRowCore, getPointOfAttachment, getPreviousRow, getRelativeRow, getRowNumber, getSubqueryTrackingArray, getTransactionController, getWarnings, isClosed, isXplainOnlyMode, markAsTopResultSet, modifiedRowCount, open, recordConstructorTime, reopenCore, requiresRelocking, returnsRows, setAfterLastRow, setBeforeFirstRow, setCompactRow, setCompatRow, 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.execute.NoPutResultSet
openCore
Methods inherited from interface org.apache.derby.iapi.sql.ResultSet
getTimeSpent
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Field Details
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tableLocked
private final boolean tableLockedIf true, the table is marked as table locked in SYS.SYSTABLES. -
unspecifiedIsolationLevel
private final boolean unspecifiedIsolationLevelIf true, the isolation level is unspecified and must be refreshed on each open. -
suppliedLockMode
private final int suppliedLockModeThe lock mode supplied through the constructor. -
isolationLevelNeedsUpdate
private boolean isolationLevelNeedsUpdateTells whether the isolation level needs to be updated. -
lockMode
int lockModeThe actual lock mode used. -
isolationLevel
int isolationLevelThe scan isolation level. -
resultRowBuilder
Object used to create and reset the candidate row. -
candidate
The candidate row, matches the shape of the rows in the underlying object to be scanned. -
accessedCols
If not null indicates the subset of columns that need to be pulled from the underlying object to be scanned. Set from the PreparedStatement's saved objects, if it exists. -
fetchRowLocations
protected boolean fetchRowLocationstrue if the scan should pick up row locations -
tableName
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indexName
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Constructor Details
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ScanResultSet
ScanResultSet(Activation activation, int resultSetNumber, int resultRowTemplate, int lockMode, boolean tableLocked, int isolationLevel, int colRefItem, double optimizerEstimatedRowCount, double optimizerEstimatedCost) throws StandardException Construct aScanResultSet
.- Parameters:
activation
- the activationresultSetNumber
- number of the result set (unique within statement)resultRowTemplate
- identifier of saved object for row templatelockMode
- lock mode (record or table)tableLocked
- true if marked as table locked in SYS.SYSTABLESisolationLevel
- language isolation level for the result setcolRefItem
- Identifier of saved object for accessedCols, -1 if need to fetch all columns.optimizerEstimatedRowCount
- estimated row countoptimizerEstimatedCost
- estimated cost- Throws:
StandardException
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Method Details
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initIsolationLevel
void initIsolationLevel()Initialize the isolation level and the lock mode. If the result set was constructed with an explicit isolation level, or if the isolation level has already been initialized, this is a no-op. All sub-classes should invoke this method from theiropenCore()
methods. -
getLockMode
private int getLockMode(int languageLevel) Get the lock mode based on the language isolation level. Always do row locking unless the isolation level is serializable or the table is marked as table locked.- Parameters:
languageLevel
- the (language) isolation level- Returns:
- lock mode
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setRowLocationsState
Determine whether this scan should return row locations- Throws:
StandardException
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translateLanguageIsolationLevel
private int translateLanguageIsolationLevel(int languageLevel) Translate isolation level from language to store.- Parameters:
languageLevel
- language isolation level- Returns:
- store isolation level
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canGetInstantaneousLocks
abstract boolean canGetInstantaneousLocks()Can we get instantaneous locks when getting share row locks at READ COMMITTED. -
getScanIsolationLevel
public int getScanIsolationLevel()Return the isolation level of the scan in the result set.- Specified by:
getScanIsolationLevel
in interfaceNoPutResultSet
- Overrides:
getScanIsolationLevel
in classBasicNoPutResultSetImpl
- Returns:
- The isolation level of the scan (in TransactionController constants).
- See Also:
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close
Close the result set.- Specified by:
close
in interfaceResultSet
- Overrides:
close
in classNoPutResultSetImpl
- Throws:
StandardException
- if an error occurs
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toXML
Description copied from interface:ResultSet
Produce an xml image of this ResultSet and its descendant ResultSets. Appends an element to the parentNode and returns the appended element.
- Specified by:
toXML
in interfaceResultSet
- Overrides:
toXML
in classBasicNoPutResultSetImpl
- Parameters:
parentNode
- Node to put content into.tag
- Element tag for content- Returns:
- the content as an element with the given tag name
- Throws:
Exception
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