Interface OptimizablePredicateList

  • All Known Implementing Classes:
    PredicateList

    public interface OptimizablePredicateList
    OptimizablePredicateList provides services for optimizing a table in a query. RESOLVE - the methods for this interface need to get defined.
    • Method Detail

      • size

        int size()
        Return the number of OptimizablePredicates in the list.
        Returns:
        integer The number of OptimizablePredicates in the list.
      • getOptPredicate

        OptimizablePredicate getOptPredicate​(int n)
        Return the nth OptimizablePredicate in the list.
        Parameters:
        n - "index" (0 based) into the list.
        Returns:
        OptimizablePredicate The nth OptimizablePredicate in the list.
      • removeOptPredicate

        void removeOptPredicate​(int predCtr)
                         throws StandardException
        Remove the OptimizablePredicate at the specified index (0-based) from the list.
        Parameters:
        predCtr - The index.
        Throws:
        StandardException - Thrown on error
      • addOptPredicate

        void addOptPredicate​(OptimizablePredicate optPredicate)
        Add the given OptimizablePredicate to the end of this list.
        Parameters:
        optPredicate - The predicate to add
      • useful

        boolean useful​(Optimizable optTable,
                       ConglomerateDescriptor cd)
                throws StandardException
        Return true if this predicate list is useful for limiting the scan on the given table using the given conglomerate.
        Parameters:
        optTable - An Optimizable for the table in question
        cd - A ConglomerateDescriptor for the conglomerate in question
        Returns:
        true if this predicate list can limit the scan
        Throws:
        StandardException - Thrown on error
      • pushUsefulPredicates

        void pushUsefulPredicates​(Optimizable optTable)
                           throws StandardException
        Determine which predicates in this list are useful for limiting the scan on the given table using its best conglomerate. Remove those predicates from this list and push them down to the given Optimizable table. The predicates are pushed down in the order of the index columns that they qualify. Also, the predicates are "marked" as start predicates, stop predicates, or qualifier predicates. Finally, the start and stop operators are set in the given Optimizable.
        Parameters:
        optTable - An Optimizable for the table in question
        Throws:
        StandardException - Thrown on error
      • classify

        void classify​(Optimizable optTable,
                      ConglomerateDescriptor cd)
               throws StandardException
        Classify the predicates in this list according to the given table and conglomerate. Each predicate can be a start key, stop key, and/or qualifier, or it can be none of the above. This method also orders the predicates to match the order of the columns in a keyed conglomerate. No ordering is done for heaps.
        Parameters:
        optTable - The Optimizable table for which to classify the predicates in this list.
        cd - The ConglomerateDescriptor for which to classify the predicates in this list.
        Throws:
        StandardException - Thrown on error
      • markAllPredicatesQualifiers

        void markAllPredicatesQualifiers()
        Mark all of the predicates as Qualifiers and set the numberOfQualifiers to reflect this. This is useful for hash joins where all of the predicates in the list to be evaluated during the probe into the hash table on a next are qualifiers.
      • hasEqualityPredicateOnOrderedColumn

        int hasEqualityPredicateOnOrderedColumn​(Optimizable optTable,
                                                int columnNumber,
                                                boolean isNullOkay)
                                         throws StandardException
        Check into the predicate list if the passed column has an equijoin predicate on it.
        Parameters:
        optTable -
        columnNumber -
        isNullOkay -
        Returns:
        the position of the predicate in the list which corresponds to the equijoin. If no quijoin predicate found, then the return value will be -1
        Throws:
        StandardException
      • hasOptimizableEqualityPredicate

        boolean hasOptimizableEqualityPredicate​(Optimizable optTable,
                                                int columnNumber,
                                                boolean isNullOkay)
                                         throws StandardException
        Is there an optimizable equality predicate on the specified column?
        Parameters:
        optTable - The optimizable the column comes from.
        columnNumber - The column number within the base table.
        isNullOkay - boolean, whether or not the IS NULL operator satisfies the search
        Returns:
        Whether or not there is an optimizable equality predicate on the specified column.
        Throws:
        StandardException - Thrown on error
      • hasOptimizableEquijoin

        boolean hasOptimizableEquijoin​(Optimizable optTable,
                                       int columnNumber)
                                throws StandardException
        Is there an optimizable equijoin on the specified column?
        Parameters:
        optTable - The optimizable the column comes from.
        columnNumber - The column number within the base table.
        Returns:
        Whether or not there is an optimizable equijoin on the specified column.
        Throws:
        StandardException - Thrown on error
      • putOptimizableEqualityPredicateFirst

        void putOptimizableEqualityPredicateFirst​(Optimizable optTable,
                                                  int columnNumber)
                                           throws StandardException
        Find the optimizable equality predicate on the specified column and make it the first predicate in this list. This is useful for hash joins where Qualifier[0] is assumed to be on the hash key.
        Parameters:
        optTable - The optimizable the column comes from.
        columnNumber - The column number within the base table.
        Throws:
        StandardException - Thrown on error
      • transferPredicates

        void transferPredicates​(OptimizablePredicateList otherList,
                                JBitSet referencedTableMap,
                                Optimizable table)
                         throws StandardException
        Transfer the predicates whose referenced set is contained by the specified referencedTableMap from this list to the other list. This is useful when splitting out a set of predicates from a larger set, like when generating a HashScanResultSet.
        Parameters:
        otherList - The predicateList to xfer to
        referencedTableMap - The table map to check against
        table - The table to order the new predicates against
        Throws:
        StandardException - Thrown on error
      • copyPredicatesToOtherList

        void copyPredicatesToOtherList​(OptimizablePredicateList otherList)
                                throws StandardException
        Non-destructive copy of all of the predicates from this list to the other list. This is useful when splitting out a set of predicates from a larger set, like when generating a HashScanResultSet.
        Parameters:
        otherList - The predicateList to xfer to
        Throws:
        StandardException - Thrown on error
      • setPredicatesAndProperties

        void setPredicatesAndProperties​(OptimizablePredicateList otherList)
                                 throws StandardException
        Sets the given list to have the same elements as this one, and the same properties as this one (number of qualifiers and start and stop predicates.
        Parameters:
        otherList - The list to set the same as this one.
        Throws:
        StandardException - Thrown on error
      • isRedundantPredicate

        boolean isRedundantPredicate​(int predNum)
        Return whether or not the specified entry in the list is a redundant predicate. This is useful for selectivity calculations because we do not want redundant predicates included in the selectivity calculation.
        Parameters:
        predNum - The entry in the list
        Returns:
        Whether or not the specified entry in the list is a redundant predicate.
      • startOperator

        int startOperator​(Optimizable optTable)
        Get the start operator for the given Optimizable for a heap or index scan.
      • stopOperator

        int stopOperator​(Optimizable optTable)
        Get the stop operator for the given Optimizable for a heap or index scan.
      • generateQualifiers

        void generateQualifiers​(ExpressionClassBuilderInterface acb,
                                MethodBuilder mb,
                                Optimizable optTable,
                                boolean absolute)
                         throws StandardException
        Generate the qualifiers for a scan. This method generates an array of Qualifiers, and fills them in with calls to the factory method for generating Qualifiers in the constructor for the activation. It stores the array of Qualifiers in a field in the activation, and returns a reference to that field. If there are no qualifiers, it initializes the array of Qualifiers to null.
        Parameters:
        acb - The ExpressionClassBuilderInterface for the class we are building
        mb - The method the generated code is going into
        optTable - The Optimizable table the Qualifiers are on
        absolute - Generate absolute column positions if true, else relative column positions (within the underlying row)
        Throws:
        StandardException - Thrown on error
      • sameStartStopPosition

        boolean sameStartStopPosition()
                               throws StandardException
        Can we use the same key for both the start and stop key. This is possible when doing an exact match on an index where there are no other sargable predicates.
        Returns:
        Whether or not we can use the same key for both the start and stop key.
        Throws:
        StandardException - Thrown on error
      • selectivity

        double selectivity​(Optimizable optTable)
                    throws StandardException
        calculate the selectivity for a set of predicates. If statistics exist for the predicates this method uses the statistics. If statistics do not exist, then simply call selectivity for each of the predicates and return the result.
        Parameters:
        optTable - the Optimizable that the predicate list restricts.
        Throws:
        StandardException
      • adjustForSortElimination

        void adjustForSortElimination​(RequiredRowOrdering ordering)
                               throws StandardException
        Walk through the predicates in this list and make any adjustments that are required to allow for proper handling of an ORDER BY clause.
        Throws:
        StandardException