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

Method Summary

Modifier and Type	Method and Description
public boolean	considerSortAvoidancePath() Check whether this optimizable's sort avoidance path should be considered.
public int	Returns: The relative 0-based column position for the column. convertAbsoluteToRelativeColumnPosition(int The absolute 0-based column position for the column. absolutePosition) Convert an absolute to a relative 0-based column position.
public CostEstimate	Returns: The estimated cost of doing the scan estimateCost(OptimizablePredicateList The predicate list to optimize against predList, ConglomerateDescriptor The conglomerate descriptor to get the cost of cd, CostEstimate The estimated cost of the part of the plan outer to this optimizable. outerCost, Optimizer The optimizer to use to help estimate the cost optimizer, RowOrdering The row ordering for all the tables in the join order, including this one. rowOrdering) Estimate the cost of scanning this Optimizable using the given predicate list with the given conglomerate.
public boolean	Returns: true means feasible feasibleJoinStrategy(OptimizablePredicateList The predicate list that has been pushed down to this optimizable predList, Optimizer The optimizer to use. optimizer) Is the current proposed join strategy for this optimizable feasible given the predicate list?
public boolean	forUpdate() Return true if this is the target table of an update
public String	getBaseTableName() Get the table name of this Optimizable.
public AccessPath	getBestAccessPath() Get the best access path for this Optimizable.
public AccessPath	getBestSortAvoidancePath() Get the best sort-avoidance path for this Optimizable.
public AccessPath	getCurrentAccessPath() Get the current access path under consideration for this Optimizable
public DataDictionary	Returns: The DataDictionary to use. getDataDictionary() Get the DataDictionary from this Optimizable.
public String	Returns: The name of this Optimizable. getName() Get the (exposed) name of this Optimizable
public int	Returns: The number of the number of columns returned by this Optimizable. getNumColumnsReturned() Get the number of the number of columns returned by this Optimizable.
public OptTrace	getOptimizerTracer() Get the optimizer tracer, if any
public Properties	Returns: The Properties list, if any, associated with this optimizable. getProperties() Get the Properties list, if any, associated with this optimizable.
public JBitSet	Returns: JBitSet Referenced table map. getReferencedTableMap() Get the map of referenced tables for this Optimizable.
public int	getResultSetNumber() Get this Optimizable's result set number
public TableDescriptor	getTableDescriptor() Get the table descriptor for this table (if any).
public int	getTableNumber() Get this Optimizable's table number
public AccessPath	getTrulyTheBestAccessPath() Get the best access path overall for this Optimizable.
public int[]	hashKeyColumns() Return the hash key column numbers, for hash join strategy
public boolean	hasLargeObjectColumns() Tell whether this Optimizable has any large object (LOB) columns.
public boolean	hasTableNumber() Return true if this Optimizable has a table number
public void	initAccessPaths(Optimizer The optimizer being used. optimizer) Init the access paths for this optimizable.
public int	initialCapacity() Return the initial capacity of the hash table, for hash join strategy
public boolean	isBaseTable() Tell whether this Optimizable represents a base table
public boolean	Returns: boolean Whether or not this is a covering index. isCoveringIndex(ConglomerateDescriptor ConglomerateDesriptor for index to consider cd) Return whether or not this is a covering index.
public boolean	isMaterializable() Tell whether this Optimizable is materializable
public boolean	Returns: Whether or not the optimizable will return at most 1 row per scan? isOneRowScan() Will the optimizable return at most 1 row per scan?
public boolean	Returns: Whether or not the optimizable the target table of an update or delete. isTargetTable() Is the optimizable the target table of an update or delete?
public boolean	Returns: Where or not this Optimizable can appear at the current location in the join order. legalJoinOrder(JBitSet The tables that have been placed so far in the join order. assignedTableMap) Can this Optimizable appear at the current location in the join order.
public float	loadFactor() Return the load factor of the hash table, for hash join strategy
public int	maxCapacity(JoinStrategy joinStrategy, int The maximum number of bytes to be used. Ignored if the user has set a maximum number of rows for the Optimizable. maxMemoryPerTable) Return the maximum capacity of the hash table, for hash join strategy
public boolean	Returns: true if the memory usage of the proposed access path is OK, false if not. memoryUsageOK(double rowCount, int maxMemoryPerTable)
public Optimizable	Returns: The (potentially new) Optimizable at the top of the tree. modifyAccessPath(JBitSet Bit map of the tables that are outer to this one in the join order. outerTables) Modify the access path for this Optimizable, as necessary.
public boolean	Returns: true means another access path was chosen, false means no more access paths to evaluate. nextAccessPath(Optimizer Optimizer to use. optimizer, OptimizablePredicateList The predicate list for this optimizable. The optimizer always passes null, and it is up to the optimizable object to pass along its own predicate list, if appropriate, when delegating this method. predList, RowOrdering The row ordering for all the outer tables in the join order. This method will add the ordering of the next access path to the given RowOrdering. rowOrdering) Choose the next access path to evaluate for this Optimizable.
public CostEstimate	Returns: The optimizer's estimated cost of the best access path. optimizeIt(Optimizer Optimizer to use. optimizer, OptimizablePredicateList The predicate list to optimize against predList, CostEstimate The CostEstimate for the outer tables in the join order, telling how many times this Optimizable will be scanned. outerCost, RowOrdering The row ordering for all the tables in the join order, including this one. rowOrdering) Choose the best access path for this Optimizable.
public boolean	optimizerTracingIsOn() Report whether optimizer tracing is on
public void	pullOptPredicates(OptimizablePredicateList The list to put the pulled predicates in. optimizablePredicates) Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList.
public boolean	Returns: Whether or not the predicate was pushed down. pushOptPredicate(OptimizablePredicate OptimizablePredicate to push down. optimizablePredicate) Push an OptimizablePredicate down, if this node accepts it.
public void	rememberAsBest(int The type of plan (one of Optimizer.NORMAL_PLAN or Optimizer.SORT_AVOIDANCE_PLAN) planType, Optimizer The OptimizerImpl that is telling this Optimizable to remember its current path as "truly the best". optimizer) Remember the current access path as the best one (so far).
public void	rememberJoinStrategyAsBest(AccessPath ap) Remember the current join strategy as the best one so far in this join order.
public void	rememberSortAvoidancePath() Mark this optimizable so that its sort avoidance path will be considered.
public void	setHashKeyColumns(int[] columnNumbers) Set the hash key column numbers, for hash join strategy
public void	setProperties(Properties The Properties list for this optimizable. tableProperties) Set the Properties list for this optimizalbe.
public void	startOptimizing(Optimizer optimizer, RowOrdering rowOrdering) Begin the optimization process for this Optimizable.
public boolean	supportsMultipleInstantiations() Tell whether this Optimizable can be instantiated multiple times
public double	Returns: <= 0 means there is no uniqueness condition > 0 means there is a uniqueness condition, and the return value is the number of rows per scan. uniqueJoin(OptimizablePredicateList The predicate list to check predList) Does this optimizable have a uniqueness condition on the given predicate list, and if so, how many unique keys will be returned per scan.
public void	updateBestPlanMap(short Indicates whether we're adding, loading, or removing a best plan for the OptimizerImpl/Optimizable. action, Object 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. 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.
public void	verifyProperties(DataDictionary The DataDictionary to use. dDictionary) Verify that the Properties list with optimizer overrides, if specified, is valid

Inherited from org.apache.derby.iapi.sql.compile.Visitable:: accept addTag taggedWith

Method Detail

considerSortAvoidancePath	back to summary
public boolean considerSortAvoidancePath() Check whether this optimizable's sort avoidance path should be considered.

convertAbsoluteToRelativeColumnPosition	back to summary
public int convertAbsoluteToRelativeColumnPosition(int absolutePosition) Convert an absolute to a relative 0-based column position. This is useful when generating qualifiers for partial rows from the store. Parameters absolutePosition:int The absolute 0-based column position for the column. Returns:int The relative 0-based column position for the column.

convertAbsoluteToRelativeColumnPosition

back to summary

public int convertAbsoluteToRelativeColumnPosition(int absolutePosition)

Convert an absolute to a relative 0-based column position. This is useful when generating qualifiers for partial rows from the store.

Parameters

absolutePosition:int: The absolute 0-based column position for the column.

Returns:int

The relative 0-based column position for the column.

estimateCost back to summary

estimateCost	back to summary
public CostEstimate estimateCost(OptimizablePredicateList predList, ConglomerateDescriptor cd, CostEstimate outerCost, Optimizer optimizer, RowOrdering rowOrdering) throws StandardException 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. Parameters predList:OptimizablePredicateList The predicate list to optimize against cd:ConglomerateDescriptor The conglomerate descriptor to get the cost of outerCost:CostEstimate The estimated cost of the part of the plan outer to this optimizable. optimizer:Optimizer The optimizer to use to help estimate the cost rowOrdering:RowOrdering The row ordering for all the tables in the join order, including this one. Returns:CostEstimate The estimated cost of doing the scan Exceptions StandardException: Thrown on error See Also `OptimizablePredicateList#classify`

public CostEstimate estimateCost(OptimizablePredicateList predList, ConglomerateDescriptor cd, CostEstimate outerCost, Optimizer optimizer, RowOrdering rowOrdering) throws StandardException

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.

Parameters

predList:OptimizablePredicateList: The predicate list to optimize against
cd:ConglomerateDescriptor: The conglomerate descriptor to get the cost of
outerCost:CostEstimate: The estimated cost of the part of the plan outer to this optimizable.
optimizer:Optimizer: The optimizer to use to help estimate the cost
rowOrdering:RowOrdering: The row ordering for all the tables in the join order, including this one.

Returns:CostEstimate

The estimated cost of doing the scan

Exceptions

StandardException:: Thrown on error

See Also

OptimizablePredicateList#classify

feasibleJoinStrategy	back to summary
public boolean feasibleJoinStrategy(OptimizablePredicateList predList, Optimizer optimizer) throws StandardException Is the current proposed join strategy for this optimizable feasible given the predicate list? Parameters predList:OptimizablePredicateList The predicate list that has been pushed down to this optimizable optimizer:Optimizer The optimizer to use. Returns:boolean true means feasible Exceptions StandardException: Thrown on error

feasibleJoinStrategy

back to summary

public boolean feasibleJoinStrategy(OptimizablePredicateList predList, Optimizer optimizer) throws StandardException

Is the current proposed join strategy for this optimizable feasible given the predicate list?

Parameters

predList:OptimizablePredicateList: The predicate list that has been pushed down to this optimizable
optimizer:Optimizer: The optimizer to use.

Returns:boolean

true means feasible

Exceptions

StandardException:: Thrown on error

forUpdate	back to summary
public boolean forUpdate() Return true if this is the target table of an update

getBaseTableName	back to summary
public String getBaseTableName() Get the table name of this Optimizable. Only base tables have table names (by the time we use this method, all views will have been resolved).

getBestAccessPath	back to summary
public AccessPath getBestAccessPath() Get the best access path for this Optimizable.

getBestSortAvoidancePath	back to summary
public AccessPath getBestSortAvoidancePath() Get the best sort-avoidance path for this Optimizable.

getCurrentAccessPath	back to summary
public AccessPath getCurrentAccessPath() Get the current access path under consideration for this Optimizable

getDataDictionary	back to summary
public DataDictionary getDataDictionary() throws StandardException Get the DataDictionary from this Optimizable. This is useful for code generation because we need to get the constraint name if scanning a back index so that RunTimeStatistics can display the correct info. Returns:DataDictionary The DataDictionary to use. Exceptions StandardException: Thrown on error

getDataDictionary

back to summary

public DataDictionary getDataDictionary() throws StandardException

Get the DataDictionary from this Optimizable. This is useful for code generation because we need to get the constraint name if scanning a back index so that RunTimeStatistics can display the correct info.

Returns:DataDictionary

The DataDictionary to use.

Exceptions

StandardException:: Thrown on error

getName	back to summary
public String getName() throws StandardException Get the (exposed) name of this Optimizable Returns:String The name of this Optimizable. Exceptions StandardException: Thrown on error

getName

back to summary

public String getName() throws StandardException

Get the (exposed) name of this Optimizable

Returns:String

The name of this Optimizable.

Exceptions

StandardException:: Thrown on error

getNumColumnsReturned	back to summary
public int getNumColumnsReturned() Get the number of the number of columns returned by this Optimizable. Returns:int The number of the number of columns returned by this Optimizable.

getNumColumnsReturned

back to summary

public int getNumColumnsReturned()

Get the number of the number of columns returned by this Optimizable.

Returns:int: The number of the number of columns returned by this Optimizable.

getOptimizerTracer	back to summary
public OptTrace getOptimizerTracer() Get the optimizer tracer, if any

getProperties	back to summary
public Properties getProperties() Get the Properties list, if any, associated with this optimizable. Returns:Properties The Properties list, if any, associated with this optimizable.

getProperties

back to summary

public Properties getProperties()

Get the Properties list, if any, associated with this optimizable.

Returns:Properties: The Properties list, if any, associated with this optimizable.

getReferencedTableMap	back to summary
public JBitSet getReferencedTableMap() Get the map of referenced tables for this Optimizable. Returns:JBitSet JBitSet Referenced table map.

getReferencedTableMap

back to summary

public JBitSet getReferencedTableMap()

Get the map of referenced tables for this Optimizable.

Returns:JBitSet: JBitSet Referenced table map.

getResultSetNumber	back to summary
public int getResultSetNumber() Get this Optimizable's result set number

getTableDescriptor	back to summary
public TableDescriptor getTableDescriptor() Get the table descriptor for this table (if any). Only base tables have table descriptors - for the rest of the optimizables, this method returns null.

getTableNumber	back to summary
public int getTableNumber() Get this Optimizable's table number

getTrulyTheBestAccessPath	back to summary
public AccessPath getTrulyTheBestAccessPath() Get the best access path overall for this Optimizable.

hashKeyColumns	back to summary
public int[] hashKeyColumns() Return the hash key column numbers, for hash join strategy

hasLargeObjectColumns	back to summary
public boolean hasLargeObjectColumns() Tell whether this Optimizable has any large object (LOB) columns.

hasTableNumber	back to summary
public boolean hasTableNumber() Return true if this Optimizable has a table number

initAccessPaths	back to summary
public void initAccessPaths(Optimizer optimizer) Init the access paths for this optimizable. Parameters optimizer:Optimizer The optimizer being used.

initAccessPaths

back to summary

public void initAccessPaths(Optimizer optimizer)

Init the access paths for this optimizable.

Parameters

optimizer:Optimizer: The optimizer being used.

initialCapacity	back to summary
public int initialCapacity() Return the initial capacity of the hash table, for hash join strategy

isBaseTable	back to summary
public boolean isBaseTable() Tell whether this Optimizable represents a base table

isCoveringIndex	back to summary
public boolean isCoveringIndex(ConglomerateDescriptor cd) throws StandardException Return whether or not this is a covering index. We expect to call this during generation, after access path selection is complete. Parameters cd:ConglomerateDescriptor ConglomerateDesriptor for index to consider Returns:boolean boolean Whether or not this is a covering index. Exceptions StandardException: Thrown on error

isCoveringIndex

back to summary

public boolean isCoveringIndex(ConglomerateDescriptor cd) throws StandardException

Return whether or not this is a covering index. We expect to call this during generation, after access path selection is complete.

Parameters

cd:ConglomerateDescriptor: ConglomerateDesriptor for index to consider

Returns:boolean

boolean Whether or not this is a covering index.

Exceptions

StandardException:: Thrown on error

isMaterializable	back to summary
public boolean isMaterializable() throws StandardException Tell whether this Optimizable is materializable Exceptions StandardException: Thrown on error

isMaterializable

back to summary

public boolean isMaterializable() throws StandardException

Tell whether this Optimizable is materializable

Exceptions

StandardException:: Thrown on error

isOneRowScan	back to summary
public boolean isOneRowScan() throws StandardException Will the optimizable return at most 1 row per scan? Returns:boolean Whether or not the optimizable will return at most 1 row per scan? Exceptions StandardException: Thrown on error

isOneRowScan

back to summary

public boolean isOneRowScan() throws StandardException

Will the optimizable return at most 1 row per scan?

Returns:boolean

Whether or not the optimizable will return at most 1 row per scan?

Exceptions

StandardException:: Thrown on error

isTargetTable	back to summary
public boolean isTargetTable() Is the optimizable the target table of an update or delete? Returns:boolean Whether or not the optimizable the target table of an update or delete.

isTargetTable

back to summary

public boolean isTargetTable()

Is the optimizable the target table of an update or delete?

Returns:boolean: Whether or not the optimizable the target table of an update or delete.

legalJoinOrder	back to summary
public boolean legalJoinOrder(JBitSet assignedTableMap) Can this Optimizable appear at the current location in the join order. In other words, have the Optimizable's dependencies been satisfied? Parameters assignedTableMap:JBitSet The tables that have been placed so far in the join order. Returns:boolean Where or not this Optimizable can appear at the current location in the join order.

legalJoinOrder

back to summary

public boolean legalJoinOrder(JBitSet assignedTableMap)

Can this Optimizable appear at the current location in the join order. In other words, have the Optimizable's dependencies been satisfied?

Parameters

assignedTableMap:JBitSet: The tables that have been placed so far in the join order.

Returns:boolean

Where or not this Optimizable can appear at the current location in the join order.

loadFactor	back to summary
public float loadFactor() Return the load factor of the hash table, for hash join strategy

maxCapacity	back to summary
public int maxCapacity(JoinStrategy joinStrategy, int maxMemoryPerTable) throws StandardException Return the maximum capacity of the hash table, for hash join strategy Parameters maxMemoryPerTable:int The maximum number of bytes to be used. Ignored if the user has set a maximum number of rows for the Optimizable. Exceptions StandardException: Standard error policy

maxCapacity

back to summary

public int maxCapacity(JoinStrategy joinStrategy, int maxMemoryPerTable) throws StandardException

Return the maximum capacity of the hash table, for hash join strategy

Parameters

maxMemoryPerTable:int: The maximum number of bytes to be used. Ignored if the user has set a maximum number of rows for the Optimizable.

Exceptions

StandardException:: Standard error policy

memoryUsageOK	back to summary
public boolean memoryUsageOK(double rowCount, int maxMemoryPerTable) throws StandardException Returns:boolean true if the memory usage of the proposed access path is OK, false if not. Exceptions StandardException: standard error policy

modifyAccessPath	back to summary
public Optimizable modifyAccessPath(JBitSet outerTables) throws StandardException Modify the access path for this Optimizable, as necessary. This includes things like adding a result set to translate from index rows to base rows Parameters outerTables:JBitSet Bit map of the tables that are outer to this one in the join order. Returns:Optimizable The (potentially new) Optimizable at the top of the tree. Exceptions StandardException: Thrown on error

modifyAccessPath

back to summary

public Optimizable modifyAccessPath(JBitSet outerTables) throws StandardException

Modify the access path for this Optimizable, as necessary. This includes things like adding a result set to translate from index rows to base rows

Parameters

outerTables:JBitSet: Bit map of the tables that are outer to this one in the join order.

Returns:Optimizable

The (potentially new) Optimizable at the top of the tree.

Exceptions

StandardException:: Thrown on error

nextAccessPath	back to summary
public boolean nextAccessPath(Optimizer optimizer, OptimizablePredicateList predList, RowOrdering rowOrdering) throws StandardException Choose the next access path to evaluate for this Optimizable. Parameters optimizer:Optimizer Optimizer to use. predList:OptimizablePredicateList The predicate list for this optimizable. The optimizer always passes null, and it is up to the optimizable object to pass along its own predicate list, if appropriate, when delegating this method. rowOrdering:RowOrdering The row ordering for all the outer tables in the join order. This method will add the ordering of the next access path to the given RowOrdering. Returns:boolean true means another access path was chosen, false means no more access paths to evaluate. Exceptions StandardException: Thrown on error

nextAccessPath

back to summary

public boolean nextAccessPath(Optimizer optimizer, OptimizablePredicateList predList, RowOrdering rowOrdering) throws StandardException

Choose the next access path to evaluate for this Optimizable.

Parameters

optimizer:Optimizer: Optimizer to use.
predList:OptimizablePredicateList: The predicate list for this optimizable. The optimizer always passes null, and it is up to the optimizable object to pass along its own predicate list, if appropriate, when delegating this method.
rowOrdering:RowOrdering: The row ordering for all the outer tables in the join order. This method will add the ordering of the next access path to the given RowOrdering.

Returns:boolean

true means another access path was chosen, false means no more access paths to evaluate.

Exceptions

StandardException:: Thrown on error

optimizeIt	back to summary
public CostEstimate optimizeIt(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) throws StandardException Choose the best access path for this Optimizable. Parameters optimizer:Optimizer Optimizer to use. predList:OptimizablePredicateList The predicate list to optimize against outerCost:CostEstimate The CostEstimate for the outer tables in the join order, telling how many times this Optimizable will be scanned. rowOrdering:RowOrdering The row ordering for all the tables in the join order, including this one. Returns:CostEstimate The optimizer's estimated cost of the best access path. Exceptions StandardException: Thrown on error

optimizeIt

back to summary

public CostEstimate optimizeIt(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) throws StandardException

Choose the best access path for this Optimizable.

Parameters

optimizer:Optimizer: Optimizer to use.
predList:OptimizablePredicateList: The predicate list to optimize against
outerCost:CostEstimate: The CostEstimate for the outer tables in the join order, telling how many times this Optimizable will be scanned.
rowOrdering:RowOrdering: The row ordering for all the tables in the join order, including this one.

Returns:CostEstimate

The optimizer's estimated cost of the best access path.

Exceptions

StandardException:: Thrown on error

optimizerTracingIsOn	back to summary
public boolean optimizerTracingIsOn() Report whether optimizer tracing is on

pullOptPredicates	back to summary
public void pullOptPredicates(OptimizablePredicateList optimizablePredicates) throws StandardException Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList. Parameters optimizablePredicates:OptimizablePredicateList The list to put the pulled predicates in. Exceptions StandardException: Thrown on error

pullOptPredicates

back to summary

public void pullOptPredicates(OptimizablePredicateList optimizablePredicates) throws StandardException

Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList.

Parameters

optimizablePredicates:OptimizablePredicateList: The list to put the pulled predicates in.

Exceptions

StandardException:: Thrown on error

pushOptPredicate	back to summary
public boolean pushOptPredicate(OptimizablePredicate optimizablePredicate) throws StandardException Push an OptimizablePredicate down, if this node accepts it. Parameters optimizablePredicate:OptimizablePredicate OptimizablePredicate to push down. Returns:boolean Whether or not the predicate was pushed down. Exceptions StandardException: Thrown on error

pushOptPredicate

back to summary

public boolean pushOptPredicate(OptimizablePredicate optimizablePredicate) throws StandardException

Push an OptimizablePredicate down, if this node accepts it.

Parameters

optimizablePredicate:OptimizablePredicate: OptimizablePredicate to push down.

Returns:boolean

Whether or not the predicate was pushed down.

Exceptions

StandardException:: Thrown on error

rememberAsBest	back to summary
public void rememberAsBest(int planType, Optimizer optimizer) throws StandardException Remember the current access path as the best one (so far). Parameters planType:int The type of plan (one of Optimizer.NORMAL_PLAN or Optimizer.SORT_AVOIDANCE_PLAN) optimizer:Optimizer The OptimizerImpl that is telling this Optimizable to remember its current path as "truly the best". Exceptions StandardException: thrown on error.

rememberAsBest

back to summary

public void rememberAsBest(int planType, Optimizer optimizer) throws StandardException

Remember the current access path as the best one (so far).

Parameters

planType:int: The type of plan (one of Optimizer.NORMAL_PLAN or Optimizer.SORT_AVOIDANCE_PLAN)
optimizer:Optimizer: The OptimizerImpl that is telling this Optimizable to remember its current path as "truly the best".

Exceptions

StandardException:: thrown on error.

rememberJoinStrategyAsBest	back to summary
public void rememberJoinStrategyAsBest(AccessPath ap) Remember the current join strategy as the best one so far in this join order.

rememberSortAvoidancePath	back to summary
public void rememberSortAvoidancePath() Mark this optimizable so that its sort avoidance path will be considered.

setHashKeyColumns	back to summary
public void setHashKeyColumns(int[] columnNumbers) Set the hash key column numbers, for hash join strategy

setProperties	back to summary
public void setProperties(Properties tableProperties) Set the Properties list for this optimizalbe. Parameters tableProperties:Properties The Properties list for this optimizable.

setProperties

back to summary

public void setProperties(Properties tableProperties)

Set the Properties list for this optimizalbe.

Parameters

tableProperties:Properties: The Properties list for this optimizable.

startOptimizing	back to summary
public void startOptimizing(Optimizer optimizer, RowOrdering rowOrdering) Begin the optimization process for this Optimizable. This can be called many times for an Optimizable while optimizing a query - it will typically be called every time the Optimizable is placed in a potential join order.

supportsMultipleInstantiations	back to summary
public boolean supportsMultipleInstantiations() Tell whether this Optimizable can be instantiated multiple times

uniqueJoin	back to summary
public double uniqueJoin(OptimizablePredicateList predList) throws StandardException Does this optimizable have a uniqueness condition on the given predicate list, and if so, how many unique keys will be returned per scan. Parameters predList:OptimizablePredicateList The predicate list to check Returns:double <= 0 means there is no uniqueness condition > 0 means there is a uniqueness condition, and the return value is the number of rows per scan. Exceptions StandardException: Thrown on error

uniqueJoin

back to summary

public double uniqueJoin(OptimizablePredicateList predList) throws StandardException

Does this optimizable have a uniqueness condition on the given predicate list, and if so, how many unique keys will be returned per scan.

Parameters

predList:OptimizablePredicateList: The predicate list to check

Returns:double

<= 0 means there is no uniqueness condition > 0 means there is a uniqueness condition, and the return value is the number of rows per scan.

Exceptions

StandardException:: Thrown on error

updateBestPlanMap	back to summary
public void updateBestPlanMap(short action, Object planKey) throws StandardException 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. Parameters action:short Indicates whether we're adding, loading, or removing a best plan for the OptimizerImpl/Optimizable. planKey:Object 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.

updateBestPlanMap

back to summary

public void updateBestPlanMap(short action, Object planKey) throws StandardException

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.

Parameters

action:short: Indicates whether we're adding, loading, or removing a best plan for the OptimizerImpl/Optimizable.
planKey:Object: 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.

verifyProperties	back to summary
public void verifyProperties(DataDictionary dDictionary) throws StandardException Verify that the Properties list with optimizer overrides, if specified, is valid Parameters dDictionary:DataDictionary The DataDictionary to use. Exceptions StandardException: Thrown on error

verifyProperties

back to summary

public void verifyProperties(DataDictionary dDictionary) throws StandardException

Verify that the Properties list with optimizer overrides, if specified, is valid

Parameters

dDictionary:DataDictionary: The DataDictionary to use.

Exceptions

StandardException:: Thrown on error

public Interface Optimizable

Method Summary

Method Detail