Class SingleChildResultSetNode

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 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 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
SingleChildResultSetNode(ResultSetNode childResult, 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) 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(String name, 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, 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(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(String name, boolean baseTable)	Return whether or not this ResultSetNode contains a subquery with a reference to the specified target.
void	updateBestPlanMap(short action, 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 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 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 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 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

childResult

ResultSetNode childResult

ResultSetNode under the SingleChildResultSetNode

hasTrulyTheBestAccessPath

protected boolean hasTrulyTheBestAccessPath

Constructor Details

SingleChildResultSetNode

SingleChildResultSetNode(ResultSetNode childResult,
 Properties tableProperties,
 ContextManager cm)

Method Details

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(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(Optimizer)

updateBestPlanMap

public void updateBestPlanMap(short action,
 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(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(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(String name,
 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,
 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