Interface Optimizable
- All Superinterfaces:
Visitable
- All Known Implementing Classes:
CurrentOfNode
,DistinctNode
,FromBaseTable
,FromSubquery
,FromTable
,FromVTI
,GroupByNode
,HalfOuterJoinNode
,HashTableNode
,IndexToBaseRowNode
,IntersectOrExceptNode
,JoinNode
,MaterializeResultSetNode
,NormalizeResultSetNode
,OrderByNode
,ProjectRestrictNode
,RowCountNode
,RowResultSetNode
,ScrollInsensitiveResultSetNode
,SetOperatorNode
,SingleChildResultSetNode
,TableOperatorNode
,UnionNode
,WindowResultSetNode
Optimizable provides services for optimizing a table in a query.
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Method Summary
Modifier and TypeMethodDescriptionboolean
Check whether this optimizable's sort avoidance path should be considered.int
convertAbsoluteToRelativeColumnPosition
(int absolutePosition) Convert an absolute to a relative 0-based column position.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
feasibleJoinStrategy
(OptimizablePredicateList predList, Optimizer optimizer) Is the current proposed join strategy for this optimizable feasible given the predicate list?boolean
Return true if this is the target table of an updateGet the table name of this Optimizable.Get the best access path for this Optimizable.Get the best sort-avoidance path for this Optimizable.Get the current access path under consideration for this OptimizableGet the DataDictionary from this Optimizable.getName()
Get the (exposed) name of this Optimizableint
Get the number of the number of columns returned by this Optimizable.Get the optimizer tracer, if anyGet the Properties list, if any, associated with this optimizable.Get the map of referenced tables for this Optimizable.int
Get this Optimizable's result set numberGet the table descriptor for this table (if any).int
Get this Optimizable's table numberGet the best access path overall for this Optimizable.int[]
Return the hash key column numbers, for hash join strategyboolean
Tell whether this Optimizable has any large object (LOB) columns.boolean
Return true if this Optimizable has a table numbervoid
initAccessPaths
(Optimizer optimizer) Init the access paths for this optimizable.int
Return the initial capacity of the hash table, for hash join strategyboolean
Tell whether this Optimizable represents a base tableboolean
Return whether or not this is a covering index.boolean
Tell whether this Optimizable is materializableboolean
Will the optimizable return at most 1 row per scan?boolean
Is the optimizable the target table of an update or delete?boolean
legalJoinOrder
(JBitSet assignedTableMap) Can this Optimizable appear at the current location in the join order.float
Return the load factor of the hash table, for hash join strategyint
maxCapacity
(JoinStrategy joinStrategy, int maxMemoryPerTable) Return the maximum capacity of the hash table, for hash join strategyboolean
memoryUsageOK
(double rowCount, int maxMemoryPerTable) modifyAccessPath
(JBitSet outerTables) Modify the access path for this Optimizable, as necessary.boolean
nextAccessPath
(Optimizer optimizer, OptimizablePredicateList predList, RowOrdering rowOrdering) Choose the next access path to evaluate for this Optimizable.optimizeIt
(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) Choose the best access path for this Optimizable.boolean
Report whether optimizer tracing is onvoid
pullOptPredicates
(OptimizablePredicateList optimizablePredicates) Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList.boolean
pushOptPredicate
(OptimizablePredicate optimizablePredicate) Push an OptimizablePredicate down, if this node accepts it.void
rememberAsBest
(int planType, Optimizer optimizer) Remember the current access path as the best one (so far).void
Remember the current join strategy as the best one so far in this join order.void
Mark this optimizable so that its sort avoidance path will be considered.void
setHashKeyColumns
(int[] columnNumbers) Set the hash key column numbers, for hash join strategyvoid
setProperties
(Properties tableProperties) Set the Properties list for this optimizalbe.void
startOptimizing
(Optimizer optimizer, RowOrdering rowOrdering) Begin the optimization process for this Optimizable.boolean
Tell whether this Optimizable can be instantiated multiple timesdouble
uniqueJoin
(OptimizablePredicateList 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.void
updateBestPlanMap
(short action, Object planKey) When remembering "truly the best" access path for an Optimizable, we have to keep track of which OptimizerImpl the "truly the best" access is for.void
verifyProperties
(DataDictionary dDictionary) Verify that the Properties list with optimizer overrides, if specified, is validMethods inherited from interface org.apache.derby.iapi.sql.compile.Visitable
accept, addTag, taggedWith
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Method Details
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nextAccessPath
boolean nextAccessPath(Optimizer optimizer, OptimizablePredicateList predList, RowOrdering rowOrdering) throws StandardException Choose the next access path to evaluate for this Optimizable.- Parameters:
optimizer
- Optimizer to use.predList
- 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
- 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:
- true means another access path was chosen, false means no more access paths to evaluate.
- Throws:
StandardException
- Thrown on error
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optimizeIt
CostEstimate optimizeIt(Optimizer optimizer, OptimizablePredicateList predList, CostEstimate outerCost, RowOrdering rowOrdering) throws StandardException Choose the best access path for this Optimizable.- Parameters:
optimizer
- Optimizer to use.predList
- The predicate list to optimize againstouterCost
- The CostEstimate for the outer tables in the join order, telling how many times this Optimizable will be scanned.rowOrdering
- The row ordering for all the tables in the join order, including this one.- Returns:
- The optimizer's estimated cost of the best access path.
- Throws:
StandardException
- Thrown on error
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getCurrentAccessPath
AccessPath getCurrentAccessPath()Get the current access path under consideration for this Optimizable -
getBestAccessPath
AccessPath getBestAccessPath()Get the best access path for this Optimizable. -
getBestSortAvoidancePath
AccessPath getBestSortAvoidancePath()Get the best sort-avoidance path for this Optimizable. -
getTrulyTheBestAccessPath
AccessPath getTrulyTheBestAccessPath()Get the best access path overall for this Optimizable. -
rememberSortAvoidancePath
void rememberSortAvoidancePath()Mark this optimizable so that its sort avoidance path will be considered. -
considerSortAvoidancePath
boolean considerSortAvoidancePath()Check whether this optimizable's sort avoidance path should be considered. -
rememberJoinStrategyAsBest
Remember the current join strategy as the best one so far in this join order. -
getTableDescriptor
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. -
getReferencedTableMap
JBitSet getReferencedTableMap()Get the map of referenced tables for this Optimizable.- Returns:
- JBitSet Referenced table map.
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pushOptPredicate
Push an OptimizablePredicate down, if this node accepts it.- Parameters:
optimizablePredicate
- OptimizablePredicate to push down.- Returns:
- Whether or not the predicate was pushed down.
- Throws:
StandardException
- Thrown on error
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pullOptPredicates
Pull all the OptimizablePredicates from this Optimizable and put them in the given OptimizablePredicateList.- Parameters:
optimizablePredicates
- The list to put the pulled predicates in.- Throws:
StandardException
- Thrown on error
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modifyAccessPath
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
- Bit map of the tables that are outer to this one in the join order.- Returns:
- The (potentially new) Optimizable at the top of the tree.
- Throws:
StandardException
- Thrown on error
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isCoveringIndex
Return whether or not this is a covering index. We expect to call this during generation, after access path selection is complete.- Parameters:
cd
- ConglomerateDesriptor for index to consider- Returns:
- boolean Whether or not this is a covering index.
- Throws:
StandardException
- Thrown on error
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getProperties
Properties getProperties()Get the Properties list, if any, associated with this optimizable.- Returns:
- The Properties list, if any, associated with this optimizable.
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setProperties
Set the Properties list for this optimizalbe.- Parameters:
tableProperties
- The Properties list for this optimizable.
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verifyProperties
Verify that the Properties list with optimizer overrides, if specified, is valid- Parameters:
dDictionary
- The DataDictionary to use.- Throws:
StandardException
- Thrown on error
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getName
Get the (exposed) name of this Optimizable- Returns:
- The name of this Optimizable.
- Throws:
StandardException
- Thrown on error
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getBaseTableName
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). -
convertAbsoluteToRelativeColumnPosition
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
- The absolute 0-based column position for the column.- Returns:
- The relative 0-based column position for the column.
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updateBestPlanMap
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
- Indicates whether we're adding, loading, or removing a best plan for the OptimizerImpl/Optimizable.planKey
- Object to use as the map key when adding/looking up a plan. If it is an instance of OptimizerImpl then it corresponds to an outer query; otherwise it's some Optimizable above this Optimizable that could potentially reject plans chosen by the OptimizerImpl to which this Optimizable belongs.- Throws:
StandardException
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rememberAsBest
Remember the current access path as the best one (so far).- Parameters:
planType
- The type of plan (one of Optimizer.NORMAL_PLAN or Optimizer.SORT_AVOIDANCE_PLAN)optimizer
- The OptimizerImpl that is telling this Optimizable to remember its current path as "truly the best".- Throws:
StandardException
- thrown on error.
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startOptimizing
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. -
estimateCost
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
- The predicate list to optimize againstcd
- The conglomerate descriptor to get the cost ofouterCost
- The estimated cost of the part of the plan outer to this optimizable.optimizer
- The optimizer to use to help estimate the costrowOrdering
- The row ordering for all the tables in the join order, including this one.- Returns:
- The estimated cost of doing the scan
- Throws:
StandardException
- Thrown on error- See Also:
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isBaseTable
boolean isBaseTable()Tell whether this Optimizable represents a base table -
isMaterializable
Tell whether this Optimizable is materializable- Throws:
StandardException
- Thrown on error
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supportsMultipleInstantiations
boolean supportsMultipleInstantiations()Tell whether this Optimizable can be instantiated multiple times -
hasLargeObjectColumns
boolean hasLargeObjectColumns()Tell whether this Optimizable has any large object (LOB) columns. -
getResultSetNumber
int getResultSetNumber()Get this Optimizable's result set number -
getTableNumber
int getTableNumber()Get this Optimizable's table number -
hasTableNumber
boolean hasTableNumber()Return true if this Optimizable has a table number -
forUpdate
boolean forUpdate()Return true if this is the target table of an update -
initialCapacity
int initialCapacity()Return the initial capacity of the hash table, for hash join strategy -
loadFactor
float loadFactor()Return the load factor of the hash table, for hash join strategy -
hashKeyColumns
int[] hashKeyColumns()Return the hash key column numbers, for hash join strategy -
setHashKeyColumns
void setHashKeyColumns(int[] columnNumbers) Set the hash key column numbers, for hash join strategy -
feasibleJoinStrategy
boolean feasibleJoinStrategy(OptimizablePredicateList predList, Optimizer optimizer) throws StandardException Is the current proposed join strategy for this optimizable feasible given the predicate list?- Parameters:
predList
- The predicate list that has been pushed down to this optimizableoptimizer
- The optimizer to use.- Returns:
- true means feasible
- Throws:
StandardException
- Thrown on error
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memoryUsageOK
- Parameters:
rowCount
-maxMemoryPerTable
-- Returns:
- true if the memory usage of the proposed access path is OK, false if not.
- Throws:
StandardException
- standard error policy
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maxCapacity
Return the maximum capacity of the hash table, for hash join strategy- Parameters:
maxMemoryPerTable
- The maximum number of bytes to be used. Ignored if the user has set a maximum number of rows for the Optimizable.- Throws:
StandardException
- Standard error policy
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legalJoinOrder
Can this Optimizable appear at the current location in the join order. In other words, have the Optimizable's dependencies been satisfied?- Parameters:
assignedTableMap
- The tables that have been placed so far in the join order.- Returns:
- Where or not this Optimizable can appear at the current location in the join order.
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getDataDictionary
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:
- The DataDictionary to use.
- Throws:
StandardException
- Thrown on error
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isTargetTable
boolean isTargetTable()Is the optimizable the target table of an update or delete?- Returns:
- Whether or not the optimizable the target table of an update or delete.
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getNumColumnsReturned
int getNumColumnsReturned()Get the number of the number of columns returned by this Optimizable.- Returns:
- The number of the number of columns returned by this Optimizable.
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isOneRowScan
Will the optimizable return at most 1 row per scan?- Returns:
- Whether or not the optimizable will return at most 1 row per scan?
- Throws:
StandardException
- Thrown on error
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initAccessPaths
Init the access paths for this optimizable.- Parameters:
optimizer
- The optimizer being used.
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uniqueJoin
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
- The predicate list to check- 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.
- Throws:
StandardException
- Thrown on error
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getOptimizerTracer
OptTrace getOptimizerTracer()Get the optimizer tracer, if any -
optimizerTracingIsOn
boolean optimizerTracingIsOn()Report whether optimizer tracing is on
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