DistinctNode (Apache Derby V10.14 Internals)

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
```
class DistinctNode
extends SingleChildResultSetNode
```
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.

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.derby.impl.sql.compile.ResultSetNode
  ResultSetNode.QueryExpressionClauses

Field Summary

Fields
Modifier and Type Field Description

(package private) boolean inSortedOrder
- 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
- Fields inherited from class org.apache.derby.impl.sql.compile.SingleChildResultSetNode
  childResult, hasTrulyTheBestAccessPath

Fields
Modifier and Type	Field	Description
`(package private) boolean`	`inSortedOrder`

Constructor Summary

Constructors
Constructor	Description
`DistinctNode(ResultSetNode childResult, boolean inSortedOrder, java.util.Properties tableProperties, ContextManager cm)`	Constructor for a DistinctNode.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`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)`	generate the distinct result set operating over the source result set.
`(package private) boolean`	`isOrderedOn(ColumnReference[] crs, boolean permuteOrdering, java.util.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.
`CostEstimate`	`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.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 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 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 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 interface org.apache.derby.iapi.sql.compile.Visitable
accept, addTag, taggedWith

- Field Detail
  - inSortedOrder
```
boolean inSortedOrder
```
- Constructor Detail
  - DistinctNode
```
DistinctNode(ResultSetNode childResult,
             boolean inSortedOrder,
             java.util.Properties tableProperties,
             ContextManager cm)
      throws StandardException
```
    Constructor for a DistinctNode.
    
    Parameters:
    
    childResult - The child ResultSetNode
    
    inSortedOrder - Whether or not the child ResultSetNode returns its output in sorted order.
    
    tableProperties - Properties list associated with the table
    
    cm - The context manager
    
    Throws:
    
    StandardException - Thrown on error
- Method Detail
  - 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 interface Optimizable
    
    Overrides:
    
    optimizeIt in class FromTable
    
    Parameters:
    
    optimizer - Optimizer to use.
    
    predList - The predicate list to optimize against
    
    outerCost - 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:
    
    Optimizable.optimizeIt(org.apache.derby.iapi.sql.compile.Optimizer, org.apache.derby.iapi.sql.compile.OptimizablePredicateList, org.apache.derby.iapi.sql.compile.CostEstimate, org.apache.derby.iapi.sql.compile.RowOrdering)
  - 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(org.apache.derby.iapi.sql.compile.OptimizablePredicateList, org.apache.derby.iapi.sql.dictionary.ConglomerateDescriptor, org.apache.derby.iapi.sql.compile.CostEstimate, org.apache.derby.iapi.sql.compile.Optimizer, org.apache.derby.iapi.sql.compile.RowOrdering)
  - pushOptPredicate
```
public boolean pushOptPredicate(OptimizablePredicate optimizablePredicate)
                         throws StandardException
```
    Description copied from interface: Optimizable
    
    Push an OptimizablePredicate down, if this node accepts it.
    
    Specified by:
    
    pushOptPredicate in interface Optimizable
    
    Overrides:
    
    pushOptPredicate in class FromTable
    
    Parameters:
    
    optimizablePredicate - OptimizablePredicate to push down.
    
    Returns:
    
    Whether or not the predicate was pushed down.
    
    Throws:
    
    StandardException - Thrown on error
    
    See Also:
    
    Optimizable.pushOptPredicate(org.apache.derby.iapi.sql.compile.OptimizablePredicate)
  - optimize
```
ResultSetNode optimize(DataDictionary dataDictionary,
                       PredicateList predicates,
                       double outerRows)
                throws StandardException
```
    Optimize this DistinctNode.
    
    Overrides:
    
    optimize in class SingleChildResultSetNode
    
    Parameters:
    
    dataDictionary - The DataDictionary to use for optimization
    
    predicates - 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
  - isOrderedOn
```
boolean isOrderedOn(ColumnReference[] crs,
                    boolean permuteOrdering,
                    java.util.List<FromBaseTable> fbtHolder)
```
    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 class SingleChildResultSetNode
    
    Parameters:
    
    crs - The specified ColumnReference[]
    
    permuteOrdering - Whether or not the order of the CRs in the array can be permuted
    
    fbtHolder - List that is to be filled with the FromBaseTable
    
    Returns:
    
    Whether the underlying ResultSet tree is ordered on the specified column.
  - generate
```
void generate(ActivationClassBuilder acb,
              MethodBuilder mb)
       throws StandardException
```
    generate the distinct result set operating over the source result set.
    
    Overrides:
    
    generate in class QueryTreeNode
    
    Parameters:
    
    acb - The ActivationClassBuilder for the class being built
    
    mb - The method for the generated code to go into
    
    Throws:
    
    StandardException - Thrown on error

Class DistinctNode

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.derby.impl.sql.compile.ResultSetNode

Field Summary

Fields inherited from class org.apache.derby.impl.sql.compile.FromTable

Fields inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

Fields inherited from class org.apache.derby.impl.sql.compile.SingleChildResultSetNode

Constructor Summary

Method Summary

Methods inherited from class org.apache.derby.impl.sql.compile.FromTable

Methods inherited from class java.lang.Object

Methods inherited from interface org.apache.derby.iapi.sql.compile.Optimizable

Methods inherited from class org.apache.derby.impl.sql.compile.QueryTreeNode

Methods inherited from class org.apache.derby.impl.sql.compile.ResultSetNode

Methods inherited from class org.apache.derby.impl.sql.compile.SingleChildResultSetNode

Methods inherited from interface org.apache.derby.iapi.sql.compile.Visitable

Field Detail

inSortedOrder

Constructor Detail

DistinctNode

Method Detail

optimizeIt

estimateCost

pushOptPredicate

optimize

isOrderedOn

generate