SingleChildResultSetNode (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

All Implemented Interfaces:

Optimizable, Visitable

Direct Known Subclasses:

DistinctNode, GroupByNode, HashTableNode, MaterializeResultSetNode, NormalizeResultSetNode, OrderByNode, ProjectRestrictNode, RowCountNode, ScrollInsensitiveResultSetNode, WindowResultSetNode
```
abstract class SingleChildResultSetNode
extends FromTable
```
A SingleChildResultSetNode represents a result set with a single child.

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) ResultSetNode childResult
ResultSetNode under the SingleChildResultSetNode

protected boolean 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

Fields
Modifier and Type	Field	Description
`(package private) ResultSetNode`	`childResult`	ResultSetNode under the SingleChildResultSetNode
`protected boolean`	`hasTrulyTheBestAccessPath`

Constructor Summary

Constructors
Constructor	Description
`SingleChildResultSetNode(ResultSetNode childResult, java.util.Properties tableProperties, ContextManager cm)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`(package private) void`	`acceptChildren(Visitor v)`	Accept the visitor for all visitable children of this node.
`(package private) ResultSetNode`	`addNewPredicate(Predicate predicate)`	Add a new predicate to the list.
`(package private) void`	`adjustForSortElimination()`	Notify the underlying result set tree that the optimizer has chosen to "eliminate" a sort.
`(package private) void`	`adjustForSortElimination(RequiredRowOrdering rowOrdering)`	Same goal as adjustForSortElimination above, but this version takes a RequiredRowOrdering to allow nodes to adjust based on the ORDER BY clause, if needed.
`(package private) ResultSetNode`	`changeAccessPath()`	The optimizer's decision on the access path for a result set may require the generation of extra result sets.
`(package private) void`	`decrementLevel(int decrement)`	Decrement (query block) level (0-based) for this FromTable.
`(package private) ResultSetNode`	`ensurePredicateList(int numTables)`	Ensure that the top of the RSN tree has a PredicateList.
`(package private) boolean`	`flattenableInFromSubquery(FromList fromList)`	Evaluate whether or not the subquery in a FromSubquery is flattenable.
`boolean`	`forUpdate()`	Return true if this is the target table of an update
`(package private) ResultSetNode`	`getChildResult()`	Return the childResult from this node.
`(package private) CostEstimate`	`getFinalCostEstimate()`	Get the final CostEstimate for this node.
`(package private) FromTable`	`getFromTableByName(java.lang.String name, java.lang.String schemaName, boolean exactMatch)`	Determine whether or not the specified name is an exposed name in the current query block.
`AccessPath`	`getTrulyTheBestAccessPath()`	Get the best access path overall for this Optimizable.
`void`	`initAccessPaths(Optimizer optimizer)`	Init the access paths for this optimizable.
`(package private) boolean`	`isNotExists()`	Return whether or not the underlying ResultSet tree is for a NOT EXISTS join.
`(package private) boolean`	`isOneRowResultSet()`	Return whether or not the underlying ResultSet tree will return a single row, at most.
`(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`	`modifyAccessPaths()`	Modify the access paths according to the decisions the optimizer made.
`(package private) ResultSetNode`	`optimize(DataDictionary dataDictionary, PredicateList predicates, double outerRows)`	Optimize this SingleChildResultSetNode.
`(package private) ResultSetNode`	`preprocess(int numTables, GroupByList gbl, FromList fromList)`	Put a ProjectRestrictNode on top of each FromTable in the FromList.
`(package private) void`	`printSubNodes(int depth)`	Prints the sub-nodes of this object.
`void`	`pullOptPredicates(OptimizablePredicateList optimizablePredicates)`	Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList.
`(package private) void`	`pushExpressions(PredicateList predicateList)`	Push expressions down to the first ResultSetNode which can do expression evaluation and has the same referenced table map.
`boolean`	`referencesSessionSchema()`	Return true if the node references SESSION schema tables (temporary or permanent)
`(package private) boolean`	`referencesTarget(java.lang.String name, boolean baseTable)`	Search to see if a query references the specifed table name.
`protected boolean`	`reflectionNeededForProjection()`	Determine whether we need to do reflection in order to do the projection.
`(package private) void`	`setChildResult(ResultSetNode childResult)`	Set the childResult for this node.
`(package private) void`	`setLevel(int level)`	Set the (query block) level (0-based) for this FromTable.
`(package private) boolean`	`subqueryReferencesTarget(java.lang.String name, boolean baseTable)`	Return whether or not this ResultSetNode contains a subquery with a reference to the specified target.
`void`	`updateBestPlanMap(short action, java.lang.Object planKey)`	When remembering "truly the best" access path for an Optimizable, we have to keep track of which OptimizerImpl the "truly the best" access is for.
`(package private) int`	`updateTargetLockMode()`	Get the lock mode for the target of an update statement (a delete or update).

Methods inherited from class org.apache.derby.impl.sql.compile.FromTable
assignCostEstimate, canBeOrdered, columnsAreUpdatable, considerSortAvoidancePath, convertAbsoluteToRelativeColumnPosition, cursorTargetTable, estimateCost, 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, optimizeIt, optimizeSubqueries, pushOptPredicate, 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, generate, 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
  - childResult
```
ResultSetNode childResult
```
    ResultSetNode under the SingleChildResultSetNode
  - hasTrulyTheBestAccessPath
```
protected boolean hasTrulyTheBestAccessPath
```
- Constructor Detail
  - SingleChildResultSetNode
```
SingleChildResultSetNode(ResultSetNode childResult,
                         java.util.Properties tableProperties,
                         ContextManager cm)
```
- Method Detail
  - getTrulyTheBestAccessPath
```
public AccessPath getTrulyTheBestAccessPath()
```
    Description copied from interface: Optimizable
    
    Get the best access path overall for this Optimizable.
    
    Specified by:
    
    getTrulyTheBestAccessPath in interface Optimizable
    
    Overrides:
    
    getTrulyTheBestAccessPath in class FromTable
    
    See Also:
    
    Optimizable.getTrulyTheBestAccessPath()
  - getChildResult
```
ResultSetNode getChildResult()
```
    Return the childResult from this node.
    
    Returns:
    
    ResultSetNode The childResult from this node.
  - setChildResult
```
void setChildResult(ResultSetNode childResult)
```
    Set the childResult for this node.
    
    Parameters:
    
    childResult - The new childResult for this node.
  - pullOptPredicates
```
public void pullOptPredicates(OptimizablePredicateList optimizablePredicates)
                       throws StandardException
```
    Description copied from interface: Optimizable
    
    Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList.
    
    Specified by:
    
    pullOptPredicates in interface Optimizable
    
    Overrides:
    
    pullOptPredicates in class FromTable
    
    Parameters:
    
    optimizablePredicates - The list to put the pulled predicates in.
    
    Throws:
    
    StandardException - Thrown on error
    
    See Also:
    
    Optimizable.pullOptPredicates(org.apache.derby.iapi.sql.compile.OptimizablePredicateList)
  - forUpdate
```
public boolean forUpdate()
```
    Description copied from interface: Optimizable
    
    Return true if this is the target table of an update
    
    Specified by:
    
    forUpdate in interface Optimizable
    
    Overrides:
    
    forUpdate in class FromTable
    
    See Also:
    
    Optimizable.forUpdate()
  - initAccessPaths
```
public void initAccessPaths(Optimizer optimizer)
```
    Description copied from interface: Optimizable
    
    Init the access paths for this optimizable.
    
    Specified by:
    
    initAccessPaths in interface Optimizable
    
    Overrides:
    
    initAccessPaths in class FromTable
    
    Parameters:
    
    optimizer - The optimizer being used.
    
    See Also:
    
    Optimizable.initAccessPaths(org.apache.derby.iapi.sql.compile.Optimizer)
  - updateBestPlanMap
```
public void updateBestPlanMap(short action,
                              java.lang.Object planKey)
                       throws StandardException
```
    Description copied from interface: Optimizable
    
    When remembering "truly the best" access path for an Optimizable, we have to keep track of which OptimizerImpl the "truly the best" access is for. In most queries there will only be one OptimizerImpl in question, but in cases where there are nested subqueries, there will be one OptimizerImpl for every level of nesting, and each OptimizerImpl might have its own idea of what this Optimizable's "truly the best path" access path really is. In addition, there could be Optimizables above this Optimizable that might need to override the best path chosen during optimization. So whenever we save a "truly the best" path, we take note of which Optimizer/Optimizable told us to do so. Then as each level of subquery finishes optimization, the corresponding OptimizerImpl/Optimizable can load its preferred access path into this Optimizable's trulyTheBestAccessPath field and pass it up the tree, until eventually the outer-most OptimizerImpl can choose to either use the best path that it received from below (by calling "rememberAsBest()") or else use the path that it found to be "best" for itself. This method is what allows us to keep track of which OptimizerImpl or Optimizable saved which "best plan", and allows us to load the appropriate plans after each round of optimization.
    
    Specified by:
    
    updateBestPlanMap in interface Optimizable
    
    Overrides:
    
    updateBestPlanMap in class FromTable
    
    Parameters:
    
    action - Indicates whether we're adding, loading, or removing a best plan for the OptimizerImpl/Optimizable.
    
    planKey - Object to use as the map key when adding/looking up a plan. If it is an instance of OptimizerImpl then it corresponds to an outer query; otherwise it's some Optimizable above this Optimizable that could potentially reject plans chosen by the OptimizerImpl to which this Optimizable belongs.
    
    Throws:
    
    StandardException
    
    See Also:
    
    Makes a call to add/load/remove a plan mapping for this node, and then makes the necessary call to recurse on this node's child, in order to ensure that we've handled the full plan all the way down this node's subtree.
  - 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
  - referencesTarget
```
boolean referencesTarget(java.lang.String name,
                         boolean baseTable)
                  throws StandardException
```
    Search to see if a query references the specifed table name.
    
    Overrides:
    
    referencesTarget in class ResultSetNode
    
    Parameters:
    
    name - Table name (String) to search for.
    
    baseTable - Whether or not name is for a base table
    
    Returns:
    
    true if found, else false
    
    Throws:
    
    StandardException - Thrown on error
  - referencesSessionSchema
```
public boolean referencesSessionSchema()
                                throws StandardException
```
    Return true if the node references SESSION schema tables (temporary or permanent)
    
    Overrides:
    
    referencesSessionSchema in class QueryTreeNode
    
    Returns:
    
    true if references SESSION schema tables, else false
    
    Throws:
    
    StandardException - Thrown on error
  - setLevel
```
void setLevel(int level)
```
    Set the (query block) level (0-based) for this FromTable.
    
    Overrides:
    
    setLevel in class FromTable
    
    Parameters:
    
    level - The query block level for this FromTable.
  - subqueryReferencesTarget
```
boolean subqueryReferencesTarget(java.lang.String name,
                                 boolean baseTable)
                          throws StandardException
```
    Return whether or not this ResultSetNode contains a subquery with a reference to the specified target.
    
    Overrides:
    
    subqueryReferencesTarget in class ResultSetNode
    
    Parameters:
    
    name - The table name.
    
    baseTable - Whether or not the name is for a base table.
    
    Returns:
    
    boolean Whether or not a reference to the table was found.
    
    Throws:
    
    StandardException - Thrown on error
  - preprocess
```
ResultSetNode preprocess(int numTables,
                         GroupByList gbl,
                         FromList fromList)
                  throws StandardException
```
    Put a ProjectRestrictNode on top of each FromTable in the FromList. ColumnReferences must continue to point to the same ResultColumn, so that ResultColumn must percolate up to the new PRN. However, that ResultColumn will point to a new expression, a VirtualColumnNode, which points to the FromTable and the ResultColumn that is the source for the ColumnReference. (The new PRN will have the original of the ResultColumnList and the ResultColumns from that list. The FromTable will get shallow copies of the ResultColumnList and its ResultColumns. ResultColumn.expression will remain at the FromTable, with the PRN getting a new VirtualColumnNode for each ResultColumn.expression.) We then project out the non-referenced columns. If there are no referenced columns, then the PRN's ResultColumnList will consist of a single ResultColumn whose expression is 1.
    
    Overrides:
    
    preprocess in class ResultSetNode
    
    Parameters:
    
    numTables - Number of tables in the DML Statement
    
    gbl - The group by list, if any
    
    fromList - The from list, if any
    
    Returns:
    
    The generated ProjectRestrictNode atop the original FromTable.
    
    Throws:
    
    StandardException - Thrown on error
  - addNewPredicate
```
ResultSetNode addNewPredicate(Predicate predicate)
                       throws StandardException
```
    Add a new predicate to the list. This is useful when doing subquery transformations, when we build a new predicate with the left side of the subquery operator and the subquery's result column.
    
    Overrides:
    
    addNewPredicate in class ResultSetNode
    
    Parameters:
    
    predicate - The predicate to add
    
    Returns:
    
    ResultSetNode The new top of the tree.
    
    Throws:
    
    StandardException - Thrown on error
  - pushExpressions
```
void pushExpressions(PredicateList predicateList)
              throws StandardException
```
    Push expressions down to the first ResultSetNode which can do expression evaluation and has the same referenced table map. RESOLVE - This means only pushing down single table expressions to DistinctNodes today. Once we have a better understanding of how the optimizer will work, we can push down join clauses.
    
    Overrides:
    
    pushExpressions in class FromTable
    
    Parameters:
    
    predicateList - The PredicateList.
    
    Throws:
    
    StandardException - Thrown on error
  - flattenableInFromSubquery
```
boolean flattenableInFromSubquery(FromList fromList)
```
    Evaluate whether or not the subquery in a FromSubquery is flattenable. Currently, a FSqry is flattenable if all of the following are true: o Subquery is a SelectNode. o It contains no top level subqueries. (RESOLVE - we can relax this) o It does not contain a group by or having clause o It does not contain aggregates.
    
    Overrides:
    
    flattenableInFromSubquery in class ResultSetNode
    
    Parameters:
    
    fromList - The outer from list
    
    Returns:
    
    boolean Whether or not the FromSubquery is flattenable.
  - ensurePredicateList
```
ResultSetNode ensurePredicateList(int numTables)
                           throws StandardException
```
    Ensure that the top of the RSN tree has a PredicateList.
    
    Overrides:
    
    ensurePredicateList in class ResultSetNode
    
    Parameters:
    
    numTables - The number of tables in the query.
    
    Returns:
    
    ResultSetNode A RSN tree with a node which has a PredicateList on top.
    
    Throws:
    
    StandardException - Thrown on error
  - optimize
```
ResultSetNode optimize(DataDictionary dataDictionary,
                       PredicateList predicates,
                       double outerRows)
                throws StandardException
```
    Optimize this SingleChildResultSetNode.
    
    Overrides:
    
    optimize in class ResultSetNode
    
    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
  - modifyAccessPaths
```
ResultSetNode modifyAccessPaths()
                         throws StandardException
```
    Description copied from class: ResultSetNode
    
    Modify the access paths according to the decisions the optimizer made. This can include adding project/restrict nodes, index-to-base-row nodes, etc.
    
    Overrides:
    
    modifyAccessPaths in class ResultSetNode
    
    Returns:
    
    The modified query tree
    
    Throws:
    
    StandardException - Thrown on error
    
    See Also:
    
    ResultSetNode.modifyAccessPaths()
  - changeAccessPath
```
ResultSetNode changeAccessPath()
                        throws StandardException
```
    Description copied from class: ResultSetNode
    
    The optimizer's decision on the access path for a result set may require the generation of extra result sets. For example, if it chooses an index for a FromBaseTable, we need an IndexToBaseRowNode above the FromBaseTable (and the FromBaseTable has to change its column list to match the index. This method in the parent class does not generate any extra result sets. It may be overridden in child classes.
    
    Overrides:
    
    changeAccessPath in class ResultSetNode
    
    Returns:
    
    A ResultSetNode tree modified to do any extra processing for the chosen access path
    
    Throws:
    
    StandardException - Thrown on error
    
    See Also:
    
    ResultSetNode.changeAccessPath()
  - getFromTableByName
```
FromTable getFromTableByName(java.lang.String name,
                             java.lang.String schemaName,
                             boolean exactMatch)
                      throws StandardException
```
    Determine whether or not the specified name is an exposed name in the current query block.
    
    Overrides:
    
    getFromTableByName in class FromTable
    
    Parameters:
    
    name - The specified name to search for as an exposed name.
    
    schemaName - Schema name, if non-null.
    
    exactMatch - Whether or not we need an exact match on specified schema and table names or match on table id.
    
    Returns:
    
    The FromTable, if any, with the exposed name.
    
    Throws:
    
    StandardException - Thrown on error
  - decrementLevel
```
void decrementLevel(int decrement)
```
    Decrement (query block) level (0-based) for this FromTable. This is useful when flattening a subquery.
    
    Overrides:
    
    decrementLevel in class FromTable
    
    Parameters:
    
    decrement - The amount to decrement by.
  - updateTargetLockMode
```
int updateTargetLockMode()
```
    Get the lock mode for the target of an update statement (a delete or update). The update mode will always be row for CurrentOfNodes. It will be table if there is no where clause.
    
    Overrides:
    
    updateTargetLockMode in class ResultSetNode
    
    Returns:
    
    The lock mode
    
    See Also:
    
    TransactionController
  - isOrderedOn
```
boolean isOrderedOn(ColumnReference[] crs,
                    boolean permuteOrdering,
                    java.util.List<FromBaseTable> fbtHolder)
             throws StandardException
```
    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 ResultSetNode
    
    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.
    
    Throws:
    
    StandardException - Thrown on error
  - isOneRowResultSet
```
boolean isOneRowResultSet()
                   throws StandardException
```
    Return whether or not the underlying ResultSet tree will return a single row, at most. This is important for join nodes where we can save the extra next on the right side if we know that it will return at most 1 row.
    
    Overrides:
    
    isOneRowResultSet in class ResultSetNode
    
    Returns:
    
    Whether or not the underlying ResultSet tree will return a single row.
    
    Throws:
    
    StandardException - Thrown on error
  - isNotExists
```
boolean isNotExists()
```
    Return whether or not the underlying ResultSet tree is for a NOT EXISTS join.
    
    Overrides:
    
    isNotExists in class ResultSetNode
    
    Returns:
    
    Whether or not the underlying ResultSet tree is for a NOT EXISTS.
  - reflectionNeededForProjection
```
protected boolean reflectionNeededForProjection()
```
    Determine whether we need to do reflection in order to do the projection. Reflection is only needed if there is at least 1 column which is not simply selecting the source column.
    
    Returns:
    
    Whether or not we need to do reflection in order to do the projection.
  - adjustForSortElimination
```
void adjustForSortElimination()
```
    Description copied from class: ResultSetNode
    
    Notify the underlying result set tree that the optimizer has chosen to "eliminate" a sort. Sort elimination can happen as part of preprocessing (see esp. SelectNode.preprocess(...)) or it can happen if the optimizer chooses an access path that inherently returns the rows in the correct order (also known as a "sort avoidance" plan). In either case we drop the sort and rely on the underlying result set tree to return its rows in the correct order. For most types of ResultSetNodes we automatically get the rows in the correct order if the sort was eliminated. One exception to this rule, though, is the case of an IndexRowToBaseRowNode, for which we have to disable bulk fetching on the underlying base table. Otherwise the index scan could return rows out of order if the base table is updated while the scan is "in progress" (i.e. while the result set is open). In order to account for this (and potentially other, similar issues in the future) this method exists to notify the result set node that it is expected to return rows in the correct order. The result set can then take necessary action to satsify this requirement--such as disabling bulk fetch in the case of IndexRowToBaseRowNode. All of that said, any ResultSetNodes for which we could potentially eliminate sorts should override this method accordingly. So we don't ever expect to get here.
    
    Overrides:
    
    adjustForSortElimination in class ResultSetNode
    
    See Also:
    
    ResultSetNode.adjustForSortElimination()
  - adjustForSortElimination
```
void adjustForSortElimination(RequiredRowOrdering rowOrdering)
                       throws StandardException
```
    Description copied from class: ResultSetNode
    
    Same goal as adjustForSortElimination above, but this version takes a RequiredRowOrdering to allow nodes to adjust based on the ORDER BY clause, if needed.
    
    Overrides:
    
    adjustForSortElimination in class ResultSetNode
    
    Throws:
    
    StandardException
    
    See Also:
    
    ResultSetNode.adjustForSortElimination()
  - getFinalCostEstimate
```
CostEstimate getFinalCostEstimate()
                           throws StandardException
```
    Get the final CostEstimate for this node.
    
    Overrides:
    
    getFinalCostEstimate in class FromTable
    
    Returns:
    
    The final CostEstimate for this node, which is the final cost estimate for the child node.
    
    Throws:
    
    StandardException
  - acceptChildren
```
void acceptChildren(Visitor v)
             throws StandardException
```
    Accept the visitor for all visitable children of this node.
    
    Overrides:
    
    acceptChildren in class FromTable
    
    Parameters:
    
    v - the visitor
    
    Throws:
    
    StandardException - on error

Class SingleChildResultSetNode

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

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 interface org.apache.derby.iapi.sql.compile.Visitable

Field Detail

childResult

hasTrulyTheBestAccessPath

Constructor Detail

SingleChildResultSetNode

Method Detail

getTrulyTheBestAccessPath

getChildResult

setChildResult

pullOptPredicates

forUpdate

initAccessPaths

updateBestPlanMap

printSubNodes

referencesTarget

referencesSessionSchema

setLevel

subqueryReferencesTarget

preprocess

addNewPredicate

pushExpressions

flattenableInFromSubquery

ensurePredicateList

optimize

modifyAccessPaths

changeAccessPath

getFromTableByName

decrementLevel

updateTargetLockMode

isOrderedOn

isOneRowResultSet

isNotExists

reflectionNeededForProjection

adjustForSortElimination

adjustForSortElimination

getFinalCostEstimate

acceptChildren