Class DistinctNode
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.SingleChildResultSetNode
org.apache.derby.impl.sql.compile.DistinctNode
- All Implemented Interfaces:
Optimizable
,Visitable
A DistinctNode represents a result set for a distinct operation
on a select. It has the same description as its input result set.
For the most part, it simply delegates operations to its childResultSet,
which is currently expected to be a ProjectRestrictResultSet generated
for a SelectNode.
NOTE: A DistinctNode extends FromTable since it can exist in a FromList.
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Nested Class Summary
Nested classes/interfaces inherited from class org.apache.derby.impl.sql.compile.ResultSetNode
ResultSetNode.QueryExpressionClauses
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Field Summary
FieldsFields inherited from class org.apache.derby.impl.sql.compile.SingleChildResultSetNode
childResult, hasTrulyTheBestAccessPath
Fields inherited from class org.apache.derby.impl.sql.compile.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 org.apache.derby.impl.sql.compile.QueryTreeNode
AUTOINCREMENT_CREATE_MODIFY, AUTOINCREMENT_CYCLE, AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX
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Constructor Summary
ConstructorsConstructorDescriptionDistinctNode
(ResultSetNode childResult, boolean inSortedOrder, Properties tableProperties, ContextManager cm) Constructor for a DistinctNode. -
Method Summary
Modifier and TypeMethodDescriptionestimateCost
(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) generate the distinct result set operating over the source result set.(package private) boolean
isOrderedOn
(ColumnReference[] crs, boolean permuteOrdering, List<FromBaseTable> fbtHolder) Return whether or not the underlying ResultSet tree is ordered on the specified columns.(package private) ResultSetNode
optimize
(DataDictionary dataDictionary, PredicateList predicates, double outerRows) Optimize this DistinctNode.optimizeIt
(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) Choose the best access path for this Optimizable.boolean
pushOptPredicate
(OptimizablePredicate optimizablePredicate) Push an OptimizablePredicate down, if this node accepts it.Methods inherited from class org.apache.derby.impl.sql.compile.SingleChildResultSetNode
acceptChildren, addNewPredicate, adjustForSortElimination, adjustForSortElimination, changeAccessPath, decrementLevel, ensurePredicateList, flattenableInFromSubquery, forUpdate, getChildResult, getFinalCostEstimate, getFromTableByName, getTrulyTheBestAccessPath, initAccessPaths, isNotExists, isOneRowResultSet, modifyAccessPaths, preprocess, printSubNodes, pullOptPredicates, pushExpressions, referencesSessionSchema, referencesTarget, reflectionNeededForProjection, setChildResult, setLevel, subqueryReferencesTarget, updateBestPlanMap, updateTargetLockMode
Methods inherited from class org.apache.derby.impl.sql.compile.FromTable
assignCostEstimate, canBeOrdered, columnsAreUpdatable, considerSortAvoidancePath, convertAbsoluteToRelativeColumnPosition, cursorTargetTable, feasibleJoinStrategy, fillInReferencedTableMap, flatten, getBaseTableName, getBestAccessPath, getBestSortAvoidancePath, getCorrelationName, getCostEstimate, getCurrentAccessPath, getExposedName, getLevel, getMergeTableID, getName, getNumColumnsReturned, getOrigTableName, getProperties, getResultColumnsForList, getSchemaDescriptor, getSchemaDescriptor, getScratchCostEstimate, getTableDescriptor, getTableName, getTableNumber, getUserSpecifiedJoinStrategy, hashKeyColumns, hasLargeObjectColumns, hasTableNumber, initialCapacity, isBaseTable, isCoveringIndex, isFlattenableJoinNode, isJoinColumnForRightOuterJoin, isMaterializable, isOneRowScan, isTargetTable, legalJoinOrder, loadFactor, LOJ_reorderable, markUpdatableByCursor, maxCapacity, memoryUsageOK, modifyAccessPath, needsSpecialRCLBinding, nextAccessPath, optimizeSubqueries, rememberAsBest, rememberJoinStrategyAsBest, rememberSortAvoidancePath, resetJoinStrategies, setCostEstimateCost, setHashKeyColumns, setMergeTableID, setOrigTableName, setProperties, setTableNumber, startOptimizing, supportsMultipleInstantiations, tellRowOrderingAboutConstantColumns, toString, transformOuterJoins, uniqueJoin, verifyProperties
Methods inherited from class org.apache.derby.impl.sql.compile.ResultSetNode
assignResultSetNumber, bindExpressions, bindExpressionsWithTables, bindNonVTITables, bindResultColumns, bindResultColumns, bindTargetExpressions, bindUntypedNullsToResultColumns, bindVTITables, columnTypesAndLengthsMatch, considerMaterialization, enhanceRCLForInsert, generateNormalizationResultSet, generateResultSet, genProjectRestrict, genProjectRestrict, genProjectRestrictForReordering, getAllResultColumns, getCandidateFinalCostEstimate, getCostEstimate, getCursorTargetTable, getFromList, getMatchingColumn, getNewCostEstimate, getOptimizer, getOptimizerImpl, getRCLForInsert, getReferencedTableMap, getResultColumns, getResultSetNumber, getScratchCostEstimate, isCursorTargetTable, isInsertSource, isPossibleDistinctScan, isStatementResultSet, isUpdatableCursor, LOJgetReferencedTables, makeResultDescription, makeResultDescriptors, markAsCursorTargetTable, markForDistinctScan, markStatementResultSet, modifyAccessPaths, notCursorTargetTable, notFlattenableJoin, numDistinctAggregates, parseDefault, performMaterialization, printQueryExpressionSuffixClauses, projectResultColumns, pushOffsetFetchFirst, pushOrderByList, pushQueryExpressionSuffix, rejectParameters, rejectXMLValues, renameGeneratedResultNames, replaceOrForbidDefaults, returnsAtMostOneRow, setCandidateFinalCostEstimate, setCostEstimate, setCursorTargetTable, setInsertSource, setOptimizer, setReferencedTableMap, setResultColumns, setResultSetNumber, setResultToBooleanTrueNode, setScratchCostEstimate, setTableConstructorTypes, verifySelectStarSubquery
Methods inherited from class org.apache.derby.impl.sql.compile.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, resolveTableToSynonym, setBeginOffset, setEndOffset, setRefActionInfo, stackPrint, taggedWith, treePrint, treePrint, verifyClassExist
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface org.apache.derby.iapi.sql.compile.Optimizable
getDataDictionary, getOptimizerTracer, getReferencedTableMap, getResultSetNumber, optimizerTracingIsOn
Methods inherited from interface org.apache.derby.iapi.sql.compile.Visitable
accept, addTag, taggedWith
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Field Details
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inSortedOrder
boolean inSortedOrder
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Constructor Details
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DistinctNode
DistinctNode(ResultSetNode childResult, boolean inSortedOrder, Properties tableProperties, ContextManager cm) throws StandardException Constructor for a DistinctNode.- Parameters:
childResult
- The child ResultSetNodeinSortedOrder
- Whether or not the child ResultSetNode returns its output in sorted order.tableProperties
- Properties list associated with the tablecm
- The context manager- Throws:
StandardException
- Thrown on error
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Method Details
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optimizeIt
public CostEstimate optimizeIt(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) throws StandardException Description copied from interface:Optimizable
Choose the best access path for this Optimizable.- Specified by:
optimizeIt
in interfaceOptimizable
- Overrides:
optimizeIt
in classFromTable
- Parameters:
optimizer
- Optimizer to use.predList
- The predicate list to optimize againstouterCost
- The CostEstimate for the outer tables in the join order, telling how many times this Optimizable will be scanned.rowOrdering
- The row ordering for all the tables in the join order, including this one.- Returns:
- The optimizer's estimated cost of the best access path.
- Throws:
StandardException
- Thrown on error- See Also:
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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 interfaceOptimizable
- Overrides:
estimateCost
in classFromTable
- Parameters:
predList
- The predicate list to optimize againstcd
- The conglomerate descriptor to get the cost ofouterCost
- The estimated cost of the part of the plan outer to this optimizable.optimizer
- The optimizer to use to help estimate the costrowOrdering
- 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:
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pushOptPredicate
Description copied from interface:Optimizable
Push an OptimizablePredicate down, if this node accepts it.- Specified by:
pushOptPredicate
in interfaceOptimizable
- Overrides:
pushOptPredicate
in classFromTable
- Parameters:
optimizablePredicate
- OptimizablePredicate to push down.- Returns:
- Whether or not the predicate was pushed down.
- Throws:
StandardException
- Thrown on error- See Also:
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optimize
ResultSetNode optimize(DataDictionary dataDictionary, PredicateList predicates, double outerRows) throws StandardException Optimize this DistinctNode.- Overrides:
optimize
in classSingleChildResultSetNode
- Parameters:
dataDictionary
- The DataDictionary to use for optimizationpredicates
- The PredicateList to optimize. This should be a join predicate.outerRows
- The number of outer joining rows- Returns:
- ResultSetNode The top of the optimized subtree
- Throws:
StandardException
- Thrown on error
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isOrderedOn
Return whether or not the underlying ResultSet tree is ordered on the specified columns. RESOLVE - This method currently only considers the outermost table of the query block.- Overrides:
isOrderedOn
in classSingleChildResultSetNode
- Parameters:
crs
- The specified ColumnReference[]permuteOrdering
- Whether or not the order of the CRs in the array can be permutedfbtHolder
- List that is to be filled with the FromBaseTable- Returns:
- Whether the underlying ResultSet tree is ordered on the specified column.
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generate
generate the distinct result set operating over the source result set.- Overrides:
generate
in classQueryTreeNode
- Parameters:
acb
- The ActivationClassBuilder for the class being builtmb
- The method for the generated code to go into- Throws:
StandardException
- Thrown on error
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