Interface Optimizable

    • Method Detail

      • 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
      • 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 against
        outerCost - 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
      • 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

        void rememberJoinStrategyAsBest​(AccessPath ap)
        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.
      • pushOptPredicate

        boolean pushOptPredicate​(OptimizablePredicate optimizablePredicate)
                          throws StandardException
        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
      • pullOptPredicates

        void pullOptPredicates​(OptimizablePredicateList optimizablePredicates)
                        throws StandardException
        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
      • modifyAccessPath

        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 - 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
      • isCoveringIndex

        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 - ConglomerateDesriptor for index to consider
        Returns:
        boolean Whether or not this is a covering index.
        Throws:
        StandardException - Thrown on error
      • getProperties

        java.util.Properties getProperties()
        Get the Properties list, if any, associated with this optimizable.
        Returns:
        The Properties list, if any, associated with this optimizable.
      • setProperties

        void setProperties​(java.util.Properties tableProperties)
        Set the Properties list for this optimizalbe.
        Parameters:
        tableProperties - The Properties list for this optimizable.
      • verifyProperties

        void verifyProperties​(DataDictionary dDictionary)
                       throws StandardException
        Verify that the Properties list with optimizer overrides, if specified, is valid
        Parameters:
        dDictionary - The DataDictionary to use.
        Throws:
        StandardException - Thrown on error
      • getName

        java.lang.String getName()
                          throws StandardException
        Get the (exposed) name of this Optimizable
        Returns:
        The name of this Optimizable.
        Throws:
        StandardException - Thrown on error
      • getBaseTableName

        java.lang.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.
      • updateBestPlanMap

        void updateBestPlanMap​(short action,
                               java.lang.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 - 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
      • rememberAsBest

        void rememberAsBest​(int planType,
                            Optimizer optimizer)
                     throws StandardException
        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.
      • startOptimizing

        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.
      • isBaseTable

        boolean isBaseTable()
        Tell whether this Optimizable represents a base table
      • 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 optimizable
        optimizer - The optimizer to use.
        Returns:
        true means feasible
        Throws:
        StandardException - Thrown on error
      • memoryUsageOK

        boolean memoryUsageOK​(double rowCount,
                              int maxMemoryPerTable)
                       throws StandardException
        Parameters:
        rowCount -
        maxMemoryPerTable -
        Returns:
        true if the memory usage of the proposed access path is OK, false if not.
        Throws:
        StandardException - standard error policy
      • maxCapacity

        int maxCapacity​(JoinStrategy joinStrategy,
                        int maxMemoryPerTable)
                 throws StandardException
        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
      • legalJoinOrder

        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 - 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.
      • getDataDictionary

        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:
        The DataDictionary to use.
        Throws:
        StandardException - Thrown on error
      • 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.
      • 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.
      • isOneRowScan

        boolean isOneRowScan()
                      throws StandardException
        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
      • initAccessPaths

        void initAccessPaths​(Optimizer optimizer)
        Init the access paths for this optimizable.
        Parameters:
        optimizer - The optimizer being used.
      • uniqueJoin

        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 - 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
      • getOptimizerTracer

        OptTrace getOptimizerTracer()
        Get the optimizer tracer, if any
      • optimizerTracingIsOn

        boolean optimizerTracingIsOn()
        Report whether optimizer tracing is on