Class CurrentOfNode

java.lang.Object

org.apache.derby.impl.sql.compile.QueryTreeNode

org.apache.derby.impl.sql.compile.ResultSetNode

org.apache.derby.impl.sql.compile.FromTable

org.apache.derby.impl.sql.compile.CurrentOfNode

All Implemented Interfaces:

Optimizable, Visitable

public final class CurrentOfNode
extends FromTable

The CurrentOf operator is used by positioned DELETE and UPDATE to get the current row and location for the target cursor. The bind() operations for positioned DELETE and UPDATE add a column to the select list under the statement for the row location accessible from this node. This node is placed in the from clause of the select generated for the delete or update operation. It acts much like a FromBaseTable, using the information about the target table of the cursor to provide information.

Nested Class Summary

Nested classes/interfaces inherited from class ResultSetNode

ResultSetNode.QueryExpressionClauses

Field Summary

Fields

Modifier and Type	Field	Description
private TableName	baseTableName
private String	cursorName
private FromBaseTable	dummyTargetTable
private TableName	exposedTableName
private ExecPreparedStatement	preStmt
private CostEstimate	singleScanCostEstimate

Fields inherited from class FromTable

ADD_PLAN, bestAccessPath, bestCostEstimate, bestSortAvoidancePath, correlationName, corrTableName, currentAccessPath, hashKeyColumns, initialCapacity, level, LOAD_PLAN, loadFactor, maxCapacity, origTableName, REMOVE_PLAN, tableNumber, tableProperties, trulyTheBestAccessPath, userSpecifiedJoinStrategy

Fields inherited from class QueryTreeNode

AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX

Constructor Summary

Constructors

Constructor	Description
CurrentOfNode(String correlationName, String cursor, Properties tableProperties, ContextManager cm)

Method Summary

Modifier and Type	Method	Description
(package private) void	acceptChildren(Visitor v)	Accept the visitor for all visitable children of this node.
(package private) void	bindExpressions(FromList fromListParam)	Bind the expressions in this ResultSetNode.
(package private) ResultSetNode	bindNonVTITables(DataDictionary dataDictionary, FromList fromListParam)	Binding this FromTable means finding the prepared statement for the cursor and creating the result columns (the columns updatable on that cursor).
CostEstimate	estimateCost(OptimizablePredicateList predList, ConglomerateDescriptor cd, CostEstimate outerCost, Optimizer optimizer, RowOrdering rowOrdering)	Estimate the cost of scanning this Optimizable using the given predicate list with the given conglomerate.
(package private) void	generate(ActivationClassBuilder acb, MethodBuilder mb)	Generation on a CurrentOfNode creates a scan on the cursor, CurrentOfResultSet.
(package private) TableName	getBaseCursorTargetTableName()
(package private) String	getCursorName()
(package private) ExecPreparedStatement	getCursorStatement()	Return the CursorNode associated with a positioned update/delete.
(package private) String	getExposedName()	Get the exposed name for this table, which is the name that can be used to refer to it in the rest of the query.
(package private) TableName	getExposedTableName()
(package private) ResultColumn	getMatchingColumn(ColumnReference columnReference)	Try to find a ResultColumn in the table represented by this CurrentOfNode that matches the name in the given ColumnReference.
(package private) static CurrentOfNode	makeForMerge(String cursorName, FromBaseTable dummyTargetTable, ContextManager cm)	Construct a dummy CurrentOfNode just for compiling the DELETE action of a MERGE statement.
(package private) ResultSetNode	optimize(DataDictionary dataDictionary, PredicateList predicateList, double outerRows)	Optimize this CurrentOfNode.
(package private) ResultSetNode	preprocess(int numTables, GroupByList gbl, FromList fromList)	Preprocess a CurrentOfNode.
(package private) void	printSubNodes(int depth)	Prints the sub-nodes of this object.
String	toString()	Convert this object to a String.
int	updateTargetLockMode()	Get the lock mode for this table as the target of an update statement (a delete or update).

Methods inherited from class FromTable

assignCostEstimate, canBeOrdered, columnsAreUpdatable, considerSortAvoidancePath, convertAbsoluteToRelativeColumnPosition, cursorTargetTable, decrementLevel, feasibleJoinStrategy, fillInReferencedTableMap, flatten, forUpdate, getBaseTableName, getBestAccessPath, getBestSortAvoidancePath, getCorrelationName, getCostEstimate, getCurrentAccessPath, getFinalCostEstimate, getFromTableByName, getLevel, getMergeTableID, getName, getNumColumnsReturned, getOrigTableName, getProperties, getResultColumnsForList, getSchemaDescriptor, getSchemaDescriptor, getScratchCostEstimate, getTableDescriptor, getTableName, getTableNumber, getTrulyTheBestAccessPath, getUserSpecifiedJoinStrategy, hashKeyColumns, hasLargeObjectColumns, hasTableNumber, initAccessPaths, initialCapacity, isBaseTable, isCoveringIndex, isFlattenableJoinNode, isJoinColumnForRightOuterJoin, isMaterializable, isOneRowScan, isTargetTable, legalJoinOrder, loadFactor, LOJ_reorderable, markUpdatableByCursor, maxCapacity, memoryUsageOK, modifyAccessPath, needsSpecialRCLBinding, nextAccessPath, optimizeIt, optimizeSubqueries, pullOptPredicates, pushExpressions, pushOptPredicate, rememberAsBest, rememberJoinStrategyAsBest, rememberSortAvoidancePath, resetJoinStrategies, setCostEstimateCost, setHashKeyColumns, setLevel, setMergeTableID, setOrigTableName, setProperties, setTableNumber, startOptimizing, supportsMultipleInstantiations, tellRowOrderingAboutConstantColumns, transformOuterJoins, uniqueJoin, updateBestPlanMap, verifyProperties

Methods inherited from class ResultSetNode

addNewPredicate, adjustForSortElimination, adjustForSortElimination, assignResultSetNumber, bindExpressionsWithTables, bindResultColumns, bindResultColumns, bindTargetExpressions, bindUntypedNullsToResultColumns, bindVTITables, changeAccessPath, columnTypesAndLengthsMatch, considerMaterialization, enhanceRCLForInsert, ensurePredicateList, flattenableInFromSubquery, generateNormalizationResultSet, generateResultSet, genProjectRestrict, genProjectRestrict, genProjectRestrictForReordering, getAllResultColumns, getCandidateFinalCostEstimate, getCostEstimate, getCursorTargetTable, getFromList, getNewCostEstimate, getOptimizer, getOptimizerImpl, getRCLForInsert, getReferencedTableMap, getResultColumns, getResultSetNumber, getScratchCostEstimate, isCursorTargetTable, isInsertSource, isNotExists, isOneRowResultSet, isOrderedOn, isPossibleDistinctScan, isStatementResultSet, isUpdatableCursor, LOJgetReferencedTables, makeResultDescription, makeResultDescriptors, markAsCursorTargetTable, markForDistinctScan, markStatementResultSet, modifyAccessPaths, modifyAccessPaths, notCursorTargetTable, notFlattenableJoin, numDistinctAggregates, parseDefault, performMaterialization, printQueryExpressionSuffixClauses, projectResultColumns, pushOffsetFetchFirst, pushOrderByList, pushQueryExpressionSuffix, referencesTarget, rejectParameters, rejectXMLValues, renameGeneratedResultNames, replaceOrForbidDefaults, returnsAtMostOneRow, setCandidateFinalCostEstimate, setCostEstimate, setCursorTargetTable, setInsertSource, setOptimizer, setReferencedTableMap, setResultColumns, setResultSetNumber, setResultToBooleanTrueNode, setScratchCostEstimate, setTableConstructorTypes, subqueryReferencesTarget, verifySelectStarSubquery

Methods inherited from class QueryTreeNode

accept, addTag, addUDTUsagePriv, addUDTUsagePriv, bindOffsetFetch, bindRowMultiSet, bindUserCatalogType, bindUserType, checkReliability, checkReliability, convertDefaultNode, copyTagsFrom, createTypeDependency, debugFlush, debugPrint, disablePrivilegeCollection, formatNodeString, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContext, getContextManager, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getLongProperty, getNullNode, getOffsetOrderedNodes, getOptimizerFactory, getOptimizerTracer, getParameterTypes, getSchemaDescriptor, getSchemaDescriptor, getStatementType, getTableDescriptor, getTypeCompiler, getUDTDesc, isAtomic, isPrivilegeCollectionRequired, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, makeTableName, nodeHeader, optimizerTracingIsOn, orReliability, parseSearchCondition, parseStatement, printLabel, referencesSessionSchema, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist

Methods inherited from class Object

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

Methods inherited from interface Optimizable

getDataDictionary, getOptimizerTracer, getReferencedTableMap, getResultSetNumber, optimizerTracingIsOn

Methods inherited from interface Visitable

accept, addTag, taggedWith

Field Details

cursorName

private String cursorName

preStmt

private ExecPreparedStatement preStmt

exposedTableName

private TableName exposedTableName

baseTableName

private TableName baseTableName

singleScanCostEstimate

private CostEstimate singleScanCostEstimate

dummyTargetTable

private FromBaseTable dummyTargetTable

Constructor Details

CurrentOfNode

CurrentOfNode(String correlationName,
 String cursor,
 Properties tableProperties,
 ContextManager cm)

Method Details

makeForMerge

static CurrentOfNode makeForMerge(String cursorName,
 FromBaseTable dummyTargetTable,
 ContextManager cm)

Construct a dummy CurrentOfNode just for compiling the DELETE action of a MERGE statement.

estimateCost

public CostEstimate estimateCost(OptimizablePredicateList predList,
 ConglomerateDescriptor cd,
 CostEstimate outerCost,
 Optimizer optimizer,
 RowOrdering rowOrdering)
                          throws StandardException

Description copied from interface: Optimizable

Estimate the cost of scanning this Optimizable using the given predicate list with the given conglomerate. It is assumed that the predicate list has already been classified. This cost estimate is just for one scan, not for the life of the query.

Specified by:

estimateCost in interface Optimizable

Overrides:

estimateCost in class FromTable

Parameters:

predList - The predicate list to optimize against

cd - The conglomerate descriptor to get the cost of

outerCost - The estimated cost of the part of the plan outer to this optimizable.

optimizer - The optimizer to use to help estimate the cost

rowOrdering - The row ordering for all the tables in the join order, including this one.

Returns:

The estimated cost of doing the scan

Throws:

StandardException - Thrown on error

See Also:

• Optimizable.estimateCost(OptimizablePredicateList, ConglomerateDescriptor, CostEstimate, Optimizer, RowOrdering)

bindNonVTITables

ResultSetNode bindNonVTITables(DataDictionary dataDictionary,
 FromList fromListParam)
                        throws StandardException

Binding this FromTable means finding the prepared statement for the cursor and creating the result columns (the columns updatable on that cursor). We expect someone else to verify that the target table of the positioned update or delete is the table under this cursor.

Overrides:

bindNonVTITables in class ResultSetNode

Parameters:

dataDictionary - The DataDictionary to use for binding

fromListParam - FromList to use/append to.

Returns:

ResultSetNode Returns this.

Throws:

StandardException - Thrown on error

bindExpressions

void bindExpressions(FromList fromListParam)

Bind the expressions in this ResultSetNode. This means binding the sub-expressions, as well as figuring out what the return type is for each expression.

Overrides:

bindExpressions in class ResultSetNode

Parameters:

fromListParam - FromList to use/append to.

getMatchingColumn

ResultColumn getMatchingColumn(ColumnReference columnReference)
                        throws StandardException

Try to find a ResultColumn in the table represented by this CurrentOfNode that matches the name in the given ColumnReference.

Overrides:

getMatchingColumn in class ResultSetNode

Parameters:

columnReference - The columnReference whose name we're looking for in the given table.

Returns:

A ResultColumn whose expression is the ColumnNode that matches the ColumnReference. Returns null if there is no match.

Throws:

StandardException - Thrown on error

preprocess

ResultSetNode preprocess(int numTables,
 GroupByList gbl,
 FromList fromList)
                  throws StandardException

Preprocess a CurrentOfNode. For a CurrentOfNode, this simply means allocating a referenced table map to avoid downstream NullPointerExceptions. NOTE: There are no bits set in the referenced table map.

Overrides:

preprocess in class ResultSetNode

Parameters:

numTables - The number of tables in the DML Statement

gbl - The group by list, if any

fromList - The from list, if any

Returns:

ResultSetNode at top of preprocessed tree.

Throws:

StandardException - Thrown on error

optimize

ResultSetNode optimize(DataDictionary dataDictionary,
 PredicateList predicateList,
 double outerRows)
                throws StandardException

Optimize this CurrentOfNode. Nothing to do.

Overrides:

optimize in class ResultSetNode

Parameters:

dataDictionary - The DataDictionary to use for optimization

predicateList - The PredicateList to optimize. This should be a single-table predicate with the table the same as the table in this FromTable.

outerRows - The number of outer joining rows

Returns:

ResultSetNode The top of the optimized subtree.

Throws:

StandardException - Thrown on error

generate

void generate(ActivationClassBuilder acb,
 MethodBuilder mb)
       throws StandardException

Generation on a CurrentOfNode creates a scan on the cursor, CurrentOfResultSet.

This routine will generate and return a call of the form:

        ResultSetFactory.getCurrentOfResultSet(cursorName)
   

Overrides:

generate in class QueryTreeNode

Parameters:

acb - The ActivationClassBuilder for the class being built

mb - The execute() method to be built

Throws:

StandardException - Thrown on error

printSubNodes

void printSubNodes(int depth)

Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.

Overrides:

printSubNodes in class ResultSetNode

Parameters:

depth - The depth of this node in the tree

toString

public String toString()

Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.

Overrides:

toString in class FromTable

Returns:

This object as a String

getExposedName

String getExposedName()

Description copied from class: FromTable

Get the exposed name for this table, which is the name that can be used to refer to it in the rest of the query.

Overrides:

getExposedName in class FromTable

Returns:

The exposed name of this table.

updateTargetLockMode

public int updateTargetLockMode()

Get the lock mode for this table as the target of an update statement (a delete or update). This is implemented only for base tables and CurrentOfNodes.

Overrides:

updateTargetLockMode in class ResultSetNode

Returns:

The lock mode

See Also:

• TransactionController

getExposedTableName

TableName getExposedTableName()

getBaseCursorTargetTableName

TableName getBaseCursorTargetTableName()

getCursorName

String getCursorName()

getCursorStatement

ExecPreparedStatement getCursorStatement()

Return the CursorNode associated with a positioned update/delete.

Returns:

CursorNode The associated CursorNode.

acceptChildren

void acceptChildren(Visitor v)
             throws StandardException

Description copied from class: ResultSetNode

Accept the visitor for all visitable children of this node.

Overrides:

acceptChildren in class FromTable

Parameters:

v - the visitor

Throws:

StandardException - on error