Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.iapi.sql.compile.JoinStrategy

Method Summary

Modifier and Type	Method and Description
public boolean	bulkFetchOK() Is it OK to use bulk fetch with this join strategy?
public void	divideUpPredicateLists(Optimizable The inner table of the join innerTable, OptimizablePredicateList Initially contains all predicates. This method removes predicates from this list and moves them to other lists, as appropriate. originalRestrictionList, OptimizablePredicateList To be filled in with predicates to be pushed down to store. storeRestrictionList, OptimizablePredicateList To be filled in with predicates that are not pushed down to the store. nonStoreRestrictionList, OptimizablePredicateList Copy of predicates used to re-qualify rows, if necessary. requalificationRestrictionList, DataDictionary The DataDictionary dd) Divide up the predicates into different lists for different phases of the operation.
public boolean	Returns: Whether or not materialization is built in to the join strategy doesMaterialization() Is materialization built in to the join strategy?
public void	estimateCost(Optimizable The inner table to join with innerTable, OptimizablePredicateList The predicate list for the join predList, ConglomerateDescriptor The conglomerate descriptor (if appropriate) to get the cost of cd, CostEstimate The estimated cost of the part of the plan outer to the inner table outerCost, Optimizer The optimizer to use to help estimate the cost optimizer, CostEstimate The estimated cost of doing a single scan of the inner table, to be filled in with the cost of doing the join. costEstimate) Get the estimated cost for the join.
public boolean	Returns: true means the strategy is feasible, false means it isn't feasible(Optimizable The inner table of the join innerTable, OptimizablePredicateList The predicateList for the join predList, Optimizer The optimizer to use optimizer) Is this join strategy feasible under the circumstances?
public OptimizablePredicateList	Returns: The base predicate list. If no predicates are pulled, it may return the source predList without doing anything. getBasePredicates(OptimizablePredicateList The predicate list to pull from. predList, OptimizablePredicateList The list to put the base predicates in. basePredicates, Optimizable The inner table of the join innerTable) Get the base predicates for this join strategy.
public String	getName() Get the name of this join strategy
public String	getOperatorSymbol() Get the operator symbol used to represent this join strategy in optimizer traces
public int	Returns: Count of the expressions pushed to use as the parameters to the result set for the inner table getScanArgs(TransactionController The TransactionController tc, MethodBuilder The method to generate the arguments in mb, Optimizable The inner table of the join innerTable, OptimizablePredicateList The predicate list to be evaluated in the store storeRestrictionList, OptimizablePredicateList The predicate list to be evaluated outside of the store nonStoreRestrictionList, ExpressionClassBuilderInterface The expression class builder for the activation class we're building acb, int The amount of bulk fetch to do bulkFetch, int The saved object index of a result row template resultRowTemplate, int The item number of the column reference bit map colRefItem, int indexColItem, int The lock mode to use when scanning the table (see TransactionController). lockMode, boolean Whether or not the table is marked (in sys.systables) as always using table locking tableLocked, int Isolation level specified (or not) for scans isolationLevel, int Max memory per table maxMemoryPerTable, boolean Whether or not we are going to generate IN-list values with which to probe the inner table. genInListVals) Get the appropriate arguments to the scan for this type of join.
public String	halfOuterJoinResultSetMethodName() Get the name of the join result set method for the half outerjoin
public boolean	ignoreBulkFetch() Should we just ignore bulk fetch with this join strategy?
public boolean	Returns: Whether or not this strategy is a form of hash join. isHashJoin() Is this a form of hash join?
public String	joinResultSetMethodName() Get the name of the join result set method for the join
public int	Returns: The maximum number of rows that can be handled by this join strategy maxCapacity(int userSpecifiedCapacity, int maximum number of bytes per table maxMemoryPerTable, double number of bytes per row perRowUsage)
public boolean	multiplyBaseCostByOuterRows() Returns true if the base cost of scanning the conglomerate should be multiplied by the number of outer rows.
public double	Returns: The extra selectivity due to non-base predicates nonBasePredicateSelectivity(Optimizable The inner table of the join. innerTable, OptimizablePredicateList The original predicate list that was passed to getBasePredicates(), from which some base predicates may have been pulled. predList) Get the extra selectivity of the non-base predicates (those that were left in the predicate list by getBasePredicates() that are not applied to the scan of the base conglomerate.
public void	putBasePredicates(OptimizablePredicateList The list of predicates to put the base predicates back in. predList, OptimizablePredicateList The base predicates to put back in the list. basePredicates) Put back and base predicates that were removed from the list by getBasePredicates (see above).
public String	resultSetMethodName(boolean True means bulk fetch is being done on the inner table bulkFetch, boolean True means we are probing the inner table for rows matching a specified list of values. multiprobe, boolean True of this is a special scan to validate a check constraint. validatingCheckConstraint) Get the name of the result set method for base table scans
public int	scanCostType() Get the costing type, for use with StoreCostController.getScanCost

Method Detail

bulkFetchOK	back to summary
public boolean bulkFetchOK() Is it OK to use bulk fetch with this join strategy?

divideUpPredicateLists	back to summary
public void divideUpPredicateLists(Optimizable innerTable, OptimizablePredicateList originalRestrictionList, OptimizablePredicateList storeRestrictionList, OptimizablePredicateList nonStoreRestrictionList, OptimizablePredicateList requalificationRestrictionList, DataDictionary dd) throws StandardException Divide up the predicates into different lists for different phases of the operation. When this method is called, all of the predicates will be in restrictionList. The effect of this method is to remove all of the predicates from restrictionList except those that will be pushed down to the store as start/stop predicates or Qualifiers. The remaining predicates will be put into nonBaseTableRestrictionList. All predicate lists will be ordered as necessary for use with the conglomerate. Some operations (like hash join) materialize results, and so require requalification of rows when doing a non-covering index scan. The predicates to use for requalification are copied into baseTableRestrictionList. Parameters innerTable:Optimizable The inner table of the join originalRestrictionList:OptimizablePredicateList Initially contains all predicates. This method removes predicates from this list and moves them to other lists, as appropriate. storeRestrictionList:OptimizablePredicateList To be filled in with predicates to be pushed down to store. nonStoreRestrictionList:OptimizablePredicateList To be filled in with predicates that are not pushed down to the store. requalificationRestrictionList:OptimizablePredicateList Copy of predicates used to re-qualify rows, if necessary. dd:DataDictionary The DataDictionary Exceptions StandardException: Thrown on error

divideUpPredicateLists

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public void divideUpPredicateLists(Optimizable innerTable, OptimizablePredicateList originalRestrictionList, OptimizablePredicateList storeRestrictionList, OptimizablePredicateList nonStoreRestrictionList, OptimizablePredicateList requalificationRestrictionList, DataDictionary dd) throws StandardException

Divide up the predicates into different lists for different phases of the operation. When this method is called, all of the predicates will be in restrictionList. The effect of this method is to remove all of the predicates from restrictionList except those that will be pushed down to the store as start/stop predicates or Qualifiers. The remaining predicates will be put into nonBaseTableRestrictionList. All predicate lists will be ordered as necessary for use with the conglomerate. Some operations (like hash join) materialize results, and so require requalification of rows when doing a non-covering index scan. The predicates to use for requalification are copied into baseTableRestrictionList.

Parameters

innerTable:Optimizable: The inner table of the join
originalRestrictionList:OptimizablePredicateList: Initially contains all predicates. This method removes predicates from this list and moves them to other lists, as appropriate.
storeRestrictionList:OptimizablePredicateList: To be filled in with predicates to be pushed down to store.
nonStoreRestrictionList:OptimizablePredicateList: To be filled in with predicates that are not pushed down to the store.
requalificationRestrictionList:OptimizablePredicateList: Copy of predicates used to re-qualify rows, if necessary.
dd:DataDictionary: The DataDictionary

Exceptions

StandardException:: Thrown on error

doesMaterialization	back to summary
public boolean doesMaterialization() Is materialization built in to the join strategy? Returns:boolean Whether or not materialization is built in to the join strategy

doesMaterialization

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public boolean doesMaterialization()

Is materialization built in to the join strategy?

Returns:boolean: Whether or not materialization is built in to the join strategy

estimateCost	back to summary
public void estimateCost(Optimizable innerTable, OptimizablePredicateList predList, ConglomerateDescriptor cd, CostEstimate outerCost, Optimizer optimizer, CostEstimate costEstimate) throws StandardException Get the estimated cost for the join. Parameters innerTable:Optimizable The inner table to join with predList:OptimizablePredicateList The predicate list for the join cd:ConglomerateDescriptor The conglomerate descriptor (if appropriate) to get the cost of outerCost:CostEstimate The estimated cost of the part of the plan outer to the inner table optimizer:Optimizer The optimizer to use to help estimate the cost costEstimate:CostEstimate The estimated cost of doing a single scan of the inner table, to be filled in with the cost of doing the join. Exceptions StandardException: Thrown on error

estimateCost

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public void estimateCost(Optimizable innerTable, OptimizablePredicateList predList, ConglomerateDescriptor cd, CostEstimate outerCost, Optimizer optimizer, CostEstimate costEstimate) throws StandardException

Get the estimated cost for the join.

Parameters

innerTable:Optimizable: The inner table to join with
predList:OptimizablePredicateList: The predicate list for the join
cd:ConglomerateDescriptor: The conglomerate descriptor (if appropriate) to get the cost of
outerCost:CostEstimate: The estimated cost of the part of the plan outer to the inner table
optimizer:Optimizer: The optimizer to use to help estimate the cost
costEstimate:CostEstimate: The estimated cost of doing a single scan of the inner table, to be filled in with the cost of doing the join.

Exceptions

StandardException:: Thrown on error

feasible	back to summary
public boolean feasible(Optimizable innerTable, OptimizablePredicateList predList, Optimizer optimizer) throws StandardException Is this join strategy feasible under the circumstances? Parameters innerTable:Optimizable The inner table of the join predList:OptimizablePredicateList The predicateList for the join optimizer:Optimizer The optimizer to use Returns:boolean true means the strategy is feasible, false means it isn't Exceptions StandardException: Thrown on error

feasible

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public boolean feasible(Optimizable innerTable, OptimizablePredicateList predList, Optimizer optimizer) throws StandardException

Is this join strategy feasible under the circumstances?

Parameters

innerTable:Optimizable: The inner table of the join
predList:OptimizablePredicateList: The predicateList for the join
optimizer:Optimizer: The optimizer to use

Returns:boolean

true means the strategy is feasible, false means it isn't

Exceptions

StandardException:: Thrown on error

getBasePredicates	back to summary
public OptimizablePredicateList getBasePredicates(OptimizablePredicateList predList, OptimizablePredicateList basePredicates, Optimizable innerTable) throws StandardException Get the base predicates for this join strategy. The base predicates are the ones that can be used while scanning the table. For some join strategies (for example, nested loop), all predicates are base predicates. For other join strategies (for example, hash join), the base predicates are those that involve comparisons with constant expressions. Also, order the base predicates according to the order in the proposed conglomerate descriptor for the inner table. Parameters predList:OptimizablePredicateList The predicate list to pull from. basePredicates:OptimizablePredicateList The list to put the base predicates in. innerTable:Optimizable The inner table of the join Returns:OptimizablePredicateList The base predicate list. If no predicates are pulled, it may return the source predList without doing anything. Exceptions StandardException: Thrown on error

getBasePredicates

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public OptimizablePredicateList getBasePredicates(OptimizablePredicateList predList, OptimizablePredicateList basePredicates, Optimizable innerTable) throws StandardException

Get the base predicates for this join strategy. The base predicates are the ones that can be used while scanning the table. For some join strategies (for example, nested loop), all predicates are base predicates. For other join strategies (for example, hash join), the base predicates are those that involve comparisons with constant expressions. Also, order the base predicates according to the order in the proposed conglomerate descriptor for the inner table.

Parameters

predList:OptimizablePredicateList: The predicate list to pull from.
basePredicates:OptimizablePredicateList: The list to put the base predicates in.
innerTable:Optimizable: The inner table of the join

Returns:OptimizablePredicateList

The base predicate list. If no predicates are pulled, it may return the source predList without doing anything.

Exceptions

StandardException:: Thrown on error

getName	back to summary
public String getName() Get the name of this join strategy

getOperatorSymbol	back to summary
public String getOperatorSymbol() Get the operator symbol used to represent this join strategy in optimizer traces

getScanArgs	back to summary
public int getScanArgs(TransactionController tc, MethodBuilder mb, Optimizable innerTable, OptimizablePredicateList storeRestrictionList, OptimizablePredicateList nonStoreRestrictionList, ExpressionClassBuilderInterface acb, int bulkFetch, int resultRowTemplate, int colRefItem, int indexColItem, int lockMode, boolean tableLocked, int isolationLevel, int maxMemoryPerTable, boolean genInListVals) throws StandardException Get the appropriate arguments to the scan for this type of join. Parameters tc:TransactionController The TransactionController mb:MethodBuilder The method to generate the arguments in innerTable:Optimizable The inner table of the join storeRestrictionList:OptimizablePredicateList The predicate list to be evaluated in the store nonStoreRestrictionList:OptimizablePredicateList The predicate list to be evaluated outside of the store acb:ExpressionClassBuilderInterface The expression class builder for the activation class we're building bulkFetch:int The amount of bulk fetch to do resultRowTemplate:int The saved object index of a result row template colRefItem:int The item number of the column reference bit map lockMode:int The lock mode to use when scanning the table (see TransactionController). tableLocked:boolean Whether or not the table is marked (in sys.systables) as always using table locking isolationLevel:int Isolation level specified (or not) for scans maxMemoryPerTable:int Max memory per table genInListVals:boolean Whether or not we are going to generate IN-list values with which to probe the inner table. Returns:int Count of the expressions pushed to use as the parameters to the result set for the inner table Exceptions StandardException: Thrown on error

getScanArgs

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public int getScanArgs(TransactionController tc, MethodBuilder mb, Optimizable innerTable, OptimizablePredicateList storeRestrictionList, OptimizablePredicateList nonStoreRestrictionList, ExpressionClassBuilderInterface acb, int bulkFetch, int resultRowTemplate, int colRefItem, int indexColItem, int lockMode, boolean tableLocked, int isolationLevel, int maxMemoryPerTable, boolean genInListVals) throws StandardException

Get the appropriate arguments to the scan for this type of join.

Parameters

tc:TransactionController: The TransactionController
mb:MethodBuilder: The method to generate the arguments in
innerTable:Optimizable: The inner table of the join
storeRestrictionList:OptimizablePredicateList: The predicate list to be evaluated in the store
nonStoreRestrictionList:OptimizablePredicateList: The predicate list to be evaluated outside of the store
acb:ExpressionClassBuilderInterface: The expression class builder for the activation class we're building
bulkFetch:int: The amount of bulk fetch to do
resultRowTemplate:int: The saved object index of a result row template
colRefItem:int: The item number of the column reference bit map
lockMode:int: The lock mode to use when scanning the table (see TransactionController).
tableLocked:boolean: Whether or not the table is marked (in sys.systables) as always using table locking
isolationLevel:int: Isolation level specified (or not) for scans
maxMemoryPerTable:int: Max memory per table
genInListVals:boolean: Whether or not we are going to generate IN-list values with which to probe the inner table.

Returns:int

Count of the expressions pushed to use as the parameters to the result set for the inner table

Exceptions

StandardException:: Thrown on error

halfOuterJoinResultSetMethodName	back to summary
public String halfOuterJoinResultSetMethodName() Get the name of the join result set method for the half outerjoin

ignoreBulkFetch	back to summary
public boolean ignoreBulkFetch() Should we just ignore bulk fetch with this join strategy?

isHashJoin	back to summary
public boolean isHashJoin() Is this a form of hash join? Returns:boolean Whether or not this strategy is a form of hash join.

isHashJoin

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public boolean isHashJoin()

Is this a form of hash join?

Returns:boolean: Whether or not this strategy is a form of hash join.

joinResultSetMethodName	back to summary
public String joinResultSetMethodName() Get the name of the join result set method for the join

maxCapacity	back to summary
public int maxCapacity(int userSpecifiedCapacity, int maxMemoryPerTable, double perRowUsage) Parameters maxMemoryPerTable:int maximum number of bytes per table perRowUsage:double number of bytes per row Returns:int The maximum number of rows that can be handled by this join strategy

multiplyBaseCostByOuterRows	back to summary
public boolean multiplyBaseCostByOuterRows() Returns true if the base cost of scanning the conglomerate should be multiplied by the number of outer rows.

nonBasePredicateSelectivity	back to summary
public double nonBasePredicateSelectivity(Optimizable innerTable, OptimizablePredicateList predList) throws StandardException Get the extra selectivity of the non-base predicates (those that were left in the predicate list by getBasePredicates() that are not applied to the scan of the base conglomerate. Note For some types of join strategy, it may not remove any predicates from the original predicate list. The join strategy is expected to know when it does this, and to return 1.0 as the extra selectivity in these cases. Parameters innerTable:Optimizable The inner table of the join. predList:OptimizablePredicateList The original predicate list that was passed to getBasePredicates(), from which some base predicates may have been pulled. Returns:double The extra selectivity due to non-base predicates

nonBasePredicateSelectivity

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public double nonBasePredicateSelectivity(Optimizable innerTable, OptimizablePredicateList predList) throws StandardException

Get the extra selectivity of the non-base predicates (those that were left in the predicate list by getBasePredicates() that are not applied to the scan of the base conglomerate.

Note

For some types of join strategy, it may not remove any predicates from the original predicate list. The join strategy is expected to know when it does this, and to return 1.0 as the extra selectivity in these cases.

Parameters

innerTable:Optimizable: The inner table of the join.
predList:OptimizablePredicateList: The original predicate list that was passed to getBasePredicates(), from which some base predicates may have been pulled.

Returns:double

The extra selectivity due to non-base predicates

putBasePredicates	back to summary
public void putBasePredicates(OptimizablePredicateList predList, OptimizablePredicateList basePredicates) throws StandardException Put back and base predicates that were removed from the list by getBasePredicates (see above). Note Those join strategies that treat all predicates as base predicates may treat the get and put methods as no-ops. Parameters predList:OptimizablePredicateList The list of predicates to put the base predicates back in. basePredicates:OptimizablePredicateList The base predicates to put back in the list. Exceptions StandardException: Thrown on error

putBasePredicates

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public void putBasePredicates(OptimizablePredicateList predList, OptimizablePredicateList basePredicates) throws StandardException

Put back and base predicates that were removed from the list by getBasePredicates (see above).

Note

Those join strategies that treat all predicates as base predicates may treat the get and put methods as no-ops.

Parameters

predList:OptimizablePredicateList: The list of predicates to put the base predicates back in.
basePredicates:OptimizablePredicateList: The base predicates to put back in the list.

Exceptions

StandardException:: Thrown on error

resultSetMethodName	back to summary
public String resultSetMethodName(boolean bulkFetch, boolean multiprobe, boolean validatingCheckConstraint) Get the name of the result set method for base table scans Parameters bulkFetch:boolean True means bulk fetch is being done on the inner table multiprobe:boolean True means we are probing the inner table for rows matching a specified list of values. validatingCheckConstraint:boolean True of this is a special scan to validate a check constraint.

resultSetMethodName

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public String resultSetMethodName(boolean bulkFetch, boolean multiprobe, boolean validatingCheckConstraint)

Get the name of the result set method for base table scans

Parameters

bulkFetch:boolean: True means bulk fetch is being done on the inner table
multiprobe:boolean: True means we are probing the inner table for rows matching a specified list of values.
validatingCheckConstraint:boolean: True of this is a special scan to validate a check constraint.

scanCostType	back to summary
public int scanCostType() Get the costing type, for use with StoreCostController.getScanCost

public Interface JoinStrategy

Method Summary

Method Detail