org.apache.derby.impl.sql.compile
Class GroupByNode

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.GroupByNode

All Implemented Interfaces:

Optimizable, Visitable

public class GroupByNode

extends SingleChildResultSetNode

A GroupByNode represents a result set for a grouping operation on a select. Note that this includes a SELECT with aggregates and no grouping columns (in which case the select list is null) It has the same description as its input result set.

For the most part, it simply delegates operations to its bottomPRSet, which is currently expected to be a ProjectRestrictResultSet generated for a SelectNode.

NOTE: A GroupByNode extends FromTable since it can exist in a FromList.

There is a lot of room for optimizations here:

• agg(distinct x) group by x => agg(x) group by x (for min and max)
• min()/max() use index scans if possible, no sort may be needed.

Author:

jerry, aggregates by jamie

Field Summary

private boolean	addDistinctAggregate
private int	addDistinctAggregateColumnNum
private AggregatorInfoList	aggInfo Information that is used at execution time to process aggregates.
(package private) java.util.Vector	aggregateVector The list of all aggregates in the query block that contains this group by.
(package private) ResultSetNode	childResult ResultSetNode under the SingleChildResultSetNode
(package private) GroupByList	groupingList The GROUP BY list
protected boolean	hasTrulyTheBestAccessPath
private boolean	isInSortedOrder
(package private) FromTable	parent The parent to the GroupByNode.
private boolean	singleInputRowOptimization

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

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

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

costEstimate, cursorTargetTable, insertSource, optimizer, referencedTableMap, resultColumns, resultSetNumber, scratchCostEstimate, statementResultSet

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

AUTOINCREMENT_INC_INDEX, AUTOINCREMENT_IS_AUTOINCREMENT_INDEX, AUTOINCREMENT_START_INDEX, beginOffset, endOffset

Constructor Summary

GroupByNode()

Method Summary

Visitable	accept(Visitor v) Accept a visitor, and call v.visit() on child nodes as necessary.
private void	addAggregates() Add the extra result columns required by the aggregates to the result list.
private void	addDistinctAggregatesToOrderBy() Add any distinct aggregates to the order by list.
private void	addNewColumnsForAggregation() Add a whole slew of columns needed for aggregation.
ResultSetNode	addNewPredicate(Predicate predicate) Add a new predicate to the list.
private void	addNewPRNode() Add a new PR node for aggregation.
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	considerPostOptimizeOptimizations(boolean selectHasPredicates) Consider any optimizations after the optimizer has chosen a plan.
(package private) void	decrementLevel(int decrement) Decrement (query block) level (0-based) for this FromTable.
ResultSetNode	ensurePredicateList(int numTables) Ensure that the top of the RSN tree has a PredicateList.
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.
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
void	generate(ActivationClassBuilder acb, MethodBuilder mb) generate the sort result set operating over the source resultset.
private void	genGroupedAggregateResultSet(ActivationClassBuilder acb, MethodBuilder mb) Generate the code to evaluate grouped aggregates.
private void	genScalarAggregateResultSet(ActivationClassBuilder acb, MethodBuilder mb) Generate the code to evaluate scalar aggregates.
ResultSetNode	getChildResult() Return the childResult from this node.
private ResultColumn	getColumnReference(ResultColumn targetRC, DataDictionary dd) Method for creating a new result column referencing the one passed in.
CostEstimate	getFinalCostEstimate() Get the final CostEstimate for this node.
protected 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.
(package private) boolean	getIsInSortedOrder() Get whether or not the source is in sorted order.
FromTable	getParent() Return the parent node to this one, if there is one.
AccessPath	getTrulyTheBestAccessPath() Get the best access path overall for this Optimizable.
void	init(java.lang.Object childResult, java.lang.Object tableProperties) Initialilzer for a SingleChildResultSetNode.
void	init(java.lang.Object bottomPR, java.lang.Object groupingList, java.lang.Object aggregateVector, java.lang.Object tableProperties) Intializer for a GroupByNode.
void	initAccessPaths(Optimizer optimizer) Init the access paths for this optimizable.
boolean	isNotExists() Return whether or not the underlying ResultSet tree is for a NOT EXISTS join.
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.Vector fbtVector) Return whether or not the underlying ResultSet tree is ordered on the specified columns.
(package private) ResultColumnDescriptor[]	makeResultDescriptors(ExecutionContext ec)
(package private) void	markOrderingDependent() Notify the underlying result set tree that the result is ordering dependent.
ResultSetNode	modifyAccessPaths() Modify the access paths according to the decisions the optimizer made.
ResultSetNode	optimize(DataDictionary dataDictionary, PredicateList predicates, double outerRows) Optimize this GroupByNode.
CostEstimate	optimizeIt(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) Choose the best access path for this Optimizable.
ResultSetNode	preprocess(int numTables, GroupByList gbl, FromList fromList) Put a ProjectRestrictNode on top of each FromTable in the FromList.
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.
void	pushExpressions(PredicateList predicateList) Push expressions down to the first ResultSetNode which can do expression evaluation and has the same referenced table map.
boolean	pushOptPredicate(OptimizablePredicate optimizablePredicate) Push an OptimizablePredicate down, if this node accepts it.
boolean	referencesSessionSchema() Return true if the node references SESSION schema tables (temporary or permanent)
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	replaceDefaults(TableDescriptor ttd, ResultColumnList tcl) Replace any DEFAULTs with the associated tree for the default.
(package private) void	setChildResult(ResultSetNode childResult) Set the childResult for this node.
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.
java.lang.String	toString() Convert this object to a String.
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

areAllColumnsProjected, assignCostEstimate, canBeOrdered, considerSortAvoidancePath, convertAbsoluteToRelativeColumnPosition, cursorTargetTable, feasibleJoinStrategy, fillInReferencedTableMap, flatten, getBaseTableName, getBestAccessPath, getBestSortAvoidancePath, getCostEstimate, getCurrentAccessPath, getExposedName, getLevel, getName, getNumColumnsReturned, getProperties, getResultColumnsForList, getSchemaDescriptor, getSchemaDescriptor, getScratchCostEstimate, getTableDescriptor, getTableName, getTableNumber, getUserSpecifiedJoinStrategy, hashKeyColumns, hasTableNumber, initialCapacity, isBaseTable, isCoveringIndex, isFlattenableJoinNode, isMaterializable, isOneRowScan, isTargetTable, legalJoinOrder, loadFactor, LOJ_reorderable, markUpdatableByCursor, maxCapacity, memoryUsageOK, modifyAccessPath, needsSpecialRCLBinding, nextAccessPath, optimizeSubqueries, rememberAsBest, rememberJoinStrategyAsBest, rememberSortAvoidancePath, resetJoinStrategies, setAllColumnsProjected, setCostEstimate, setHashKeyColumns, setProperties, setTableNumber, startOptimizing, supportsMultipleInstantiations, tellRowOrderingAboutConstantColumns, transformOuterJoins, uniqueJoin, verifyProperties

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

assignResultSetNumber, bindExpressions, bindExpressionsWithTables, bindNonVTITables, bindResultColumns, bindResultColumns, bindTargetExpressions, bindUntypedNullsToResultColumns, bindVTITables, closeMethodArgument, columnTypesAndLengthsMatch, considerMaterialization, enhanceRCLForInsert, generateNormalizationResultSet, generateResultSet, genNewRCForInsert, genNormalizeResultSetNode, genProjectRestrict, genProjectRestrict, genProjectRestrictForReordering, getAllResultColumns, getCostEstimate, getCursorTargetTable, getFromList, getMatchingColumn, getNewCostEstimate, getOptimizer, getReferencedTableMap, getResultColumns, getResultSetNumber, isPossibleDistinctScan, isUpdatableCursor, LOJgetReferencedTables, makeResultDescription, markAsCursorTargetTable, markForDistinctScan, markStatementResultSet, notCursorTargetTable, notFlattenableJoin, numDistinctAggregates, parseDefault, performMaterialization, projectResultColumns, pushOrderByList, rejectParameters, rejectXMLValues, renameGeneratedResultNames, returnsAtMostOneRow, setInsertSource, setReferencedTableMap, setResultColumns, setResultToBooleanTrueNode, setTableConstructorTypes, verifySelectStarSubquery

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

bind, convertDefaultNode, debugFlush, debugPrint, executeSchemaName, executeStatementName, formatNodeString, foundString, generate, generateAuthorizeCheck, getBeginOffset, getClassFactory, getCompilerContext, getContextManager, getCursorInfo, getDataDictionary, getDependencyManager, getEndOffset, getExecutionFactory, getGenericConstantActionFactory, getIntProperty, getLanguageConnectionContext, getNodeFactory, getNodeType, getNullNode, getParameterTypes, getRowEstimate, getSchemaDescriptor, getSchemaDescriptor, getSPSName, getStatementType, getTableDescriptor, getTypeCompiler, init, init, init, init, init, init, init, init, init, init, init, init, isAtomic, isInstanceOf, isSessionSchema, isSessionSchema, makeConstantAction, makeTableName, needsSavepoint, nodeHeader, optimize, parseQueryText, printLabel, resolveTableToSynonym, setBeginOffset, setContextManager, setEndOffset, setNodeType, setRefActionInfo, 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, getReferencedTableMap, getResultSetNumber

Field Detail

groupingList

GroupByList groupingList

The GROUP BY list

aggregateVector

java.util.Vector aggregateVector

The list of all aggregates in the query block that contains this group by.

aggInfo

private AggregatorInfoList aggInfo

Information that is used at execution time to process aggregates.

parent

FromTable parent

The parent to the GroupByNode. If we need to generate a ProjectRestrict over the group by then this is set to that node. Otherwise it is null.

addDistinctAggregate

private boolean addDistinctAggregate

singleInputRowOptimization

private boolean singleInputRowOptimization

addDistinctAggregateColumnNum

private int addDistinctAggregateColumnNum

isInSortedOrder

private boolean isInSortedOrder

childResult

ResultSetNode childResult

ResultSetNode under the SingleChildResultSetNode

hasTrulyTheBestAccessPath

protected boolean hasTrulyTheBestAccessPath

Constructor Detail

GroupByNode

public GroupByNode()

Method Detail

init

public void init(java.lang.Object bottomPR,
                 java.lang.Object groupingList,
                 java.lang.Object aggregateVector,
                 java.lang.Object tableProperties)
          throws StandardException

Intializer for a GroupByNode.

Overrides:

init in class QueryTreeNode

Parameters:

bottomPR - The child FromTable

groupingList - The groupingList

aggregateVector - The vector of aggregates from the query block. Since aggregation is done at the same time as grouping, we need them here.

tableProperties - Properties list associated with the table

Throws:

StandardException - Thrown on error

getIsInSortedOrder

boolean getIsInSortedOrder()

Get whether or not the source is in sorted order.

Returns:

Whether or not the source is in sorted order.

addAggregates

private void addAggregates()
                    throws StandardException

Add the extra result columns required by the aggregates to the result list.

Throws:

standard - exception

StandardException

addDistinctAggregatesToOrderBy

private void addDistinctAggregatesToOrderBy()

Add any distinct aggregates to the order by list. Asserts that there are 0 or more distincts.

addNewPRNode

private void addNewPRNode()
                   throws StandardException

Add a new PR node for aggregation. Put the new PR under the sort.

Throws:

standard - exception

StandardException

addNewColumnsForAggregation

private void addNewColumnsForAggregation()
                                  throws StandardException

Add a whole slew of columns needed for aggregation. Basically, for each aggregate we add 2 columns: the aggregate input expression and the aggregator column. The input expression is taken directly from the aggregator node. The aggregator is the run time aggregator. We add it to the RC list as a new object coming into the sort node.

At this point this is invoked, we have the following tree:

PR - (PARENT): RCL is the original select list | PR - GROUP BY: RCL is empty | PR - FROM TABLE: RCL is empty

For each ColumnReference in PR RCL

• clone the ref
• create a new RC in the bottom RCL and set it to the col ref
• create a new RC in the GROUPBY RCL and set it to point to the bottom RC
• reset the top PR ref to point to the new GROUPBY RC For each aggregate in aggregateVector
  • create RC in FROM TABLE. Fill it with aggs Operator.
  • create RC in FROM TABLE for agg result
  • create RC in FROM TABLE for aggregator
  • create RC in GROUPBY for agg input, set it to point to FROM TABLE RC
  • create RC in GROUPBY for agg result
  • create RC in GROUPBY for aggregator
  • replace Agg with reference to RC for agg result

  Throws:

  standard - exception

  StandardException

getParent

public FromTable getParent()

Return the parent node to this one, if there is one. It will return 'this' if there is no generated node above this one.

Returns:

the parent node

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

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

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

Throws:

StandardException - Thrown on error

See Also:

Optimizable.pushOptPredicate(org.apache.derby.iapi.sql.compile.OptimizablePredicate)

toString

public java.lang.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

flattenableInFromSubquery

public 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 SingleChildResultSetNode

Parameters:

fromList - The outer from list

Returns:

boolean Whether or not the FromSubquery is flattenable.

optimize

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

Optimize this GroupByNode.

Overrides:

optimize in class SingleChildResultSetNode

Parameters:

dataDictionary - The DataDictionary to use for optimization

outerRows - The number of outer joining rows

Returns:

ResultSetNode The top of the optimized subtree

Throws:

StandardException - Thrown on error

makeResultDescriptors

ResultColumnDescriptor[] makeResultDescriptors(ExecutionContext ec)

Overrides:

makeResultDescriptors in class ResultSetNode

isOneRowResultSet

public 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 SingleChildResultSetNode

Returns:

Whether or not the underlying ResultSet tree will return a single row.

Throws:

StandardException - Thrown on error

generate

public void generate(ActivationClassBuilder acb,
                     MethodBuilder mb)
              throws StandardException

generate the sort result set operating over the source resultset. Adds distinct aggregates to the sort if necessary.

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

genScalarAggregateResultSet

private void genScalarAggregateResultSet(ActivationClassBuilder acb,
                                         MethodBuilder mb)

Generate the code to evaluate scalar aggregates.

genGroupedAggregateResultSet

private void genGroupedAggregateResultSet(ActivationClassBuilder acb,
                                          MethodBuilder mb)
                                   throws StandardException

Generate the code to evaluate grouped aggregates.

Throws:

StandardException

getColumnReference

private ResultColumn getColumnReference(ResultColumn targetRC,
                                        DataDictionary dd)
                                 throws StandardException

Method for creating a new result column referencing the one passed in.

Parameters:

targetRC - the source

dd -

Returns:

the new result column

Throws:

StandardException - on error

considerPostOptimizeOptimizations

void considerPostOptimizeOptimizations(boolean selectHasPredicates)
                                 throws StandardException

Consider any optimizations after the optimizer has chosen a plan. Optimizations include: o min optimization for scalar aggregates o max optimization for scalar aggregates

Parameters:

selectHasPredicates - true if SELECT containing this vector/scalar aggregate has a restriction

Returns:

Nothing.

Throws:

StandardException - on error

init

public void init(java.lang.Object childResult,
                 java.lang.Object tableProperties)

Initialilzer for a SingleChildResultSetNode.

Overrides:

init in class FromTable

Parameters:

childResult - The child ResultSetNode

tableProperties - Properties list associated with the table

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

public 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.

Returns:

Nothing.

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

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

See Also:

Optimizable.initAccessPaths(org.apache.derby.iapi.sql.compile.Optimizer)

printSubNodes

public 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

Returns:

Nothing

referencesTarget

public 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

public 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.

Returns:

Nothing

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

public 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

public 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

public 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

ensurePredicateList

public 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

modifyAccessPaths

public 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

public 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

protected 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

public 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.Vector fbtVector)
              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

fbtVector - Vector 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

isNotExists

public 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.

replaceDefaults

void replaceDefaults(TableDescriptor ttd,
                     ResultColumnList tcl)
               throws StandardException

Replace any DEFAULTs with the associated tree for the default.

Overrides:

replaceDefaults in class ResultSetNode

Parameters:

ttd - The TableDescriptor for the target table.

tcl - The RCL for the target table.

Throws:

StandardException - Thrown on error

markOrderingDependent

void markOrderingDependent()

Notify the underlying result set tree that the result is ordering dependent. (For example, no bulk fetch on an index if under an IndexRowToBaseRow.)

Overrides:

markOrderingDependent in class ResultSetNode

Returns:

Nothing.

getFinalCostEstimate

public CostEstimate getFinalCostEstimate()

Get the final CostEstimate for this node.

Overrides:

getFinalCostEstimate in class ResultSetNode

Returns:

The final CostEstimate for this node, which is the final cost estimate for the child node.

accept

public Visitable accept(Visitor v)
                 throws StandardException

Accept a visitor, and call v.visit() on child nodes as necessary.

Specified by:

accept in interface Visitable

Overrides:

accept in class ResultSetNode

Parameters:

v - the visitor

Throws:

StandardException - on error