Interface OptimizablePredicate

All Known Implementing Classes:
Predicate

public interface OptimizablePredicate
OptimizablePredicate provides services for optimizing predicates in a query.
  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    compareWithKnownConstant(Optimizable optTable, boolean considerParameters)
    Is this predicate a comparison with a known constant value?
    boolean
    Is this predicate an equality comparison with a constant expression?
    Get an Object representing the known constant value that the given Optimizable is being compared to.
    int
    Get the position of the index column that this predicate restricts.
    Get the map of referenced tables for this OptimizablePredicate.
    int
    hasEqualOnColumnList(int[] baseColumnPositions, Optimizable optTable)
    Returns if the predicate involves an equal operator on one of the columns specified in the baseColumnPositions.
    boolean
    Return whether or not an OptimizablePredicate contains a method call.
    boolean
    Return whether or not an OptimizablePredicate contains a subquery.
    boolean
    Is this predicate a qualifier?
    boolean
    Is this predicate a start key?
    boolean
    Is this predicate a stop key?
    void
    Tell the predicate that it is to be used as a qualifier in an index scan.
    void
    Tell the predicate that it is to be used as a column in the start key value for an index scan.
    void
    Tell the predicate that it is to be used as a column in the stop key value for an index scan.
    double
    Get a (crude) estimate of the selectivity of this predicate.
  • Method Details

    • getReferencedMap

      JBitSet getReferencedMap()
      Get the map of referenced tables for this OptimizablePredicate.
      Returns:
      JBitSet Referenced table map.
    • hasSubquery

      boolean hasSubquery()
      Return whether or not an OptimizablePredicate contains a subquery.
      Returns:
      boolean Whether or not an OptimizablePredicate includes a subquery.
    • hasMethodCall

      boolean hasMethodCall()
      Return whether or not an OptimizablePredicate contains a method call.
      Returns:
      boolean Whether or not an OptimizablePredicate includes a method call.
    • markStartKey

      void markStartKey()
      Tell the predicate that it is to be used as a column in the start key value for an index scan.
    • isStartKey

      boolean isStartKey()
      Is this predicate a start key?
    • markStopKey

      void markStopKey()
      Tell the predicate that it is to be used as a column in the stop key value for an index scan.
    • isStopKey

      boolean isStopKey()
      Is this predicate a stop key?
    • markQualifier

      void markQualifier()
      Tell the predicate that it is to be used as a qualifier in an index scan.
    • isQualifier

      boolean isQualifier()
      Is this predicate a qualifier?
    • compareWithKnownConstant

      boolean compareWithKnownConstant(Optimizable optTable, boolean considerParameters)
      Is this predicate a comparison with a known constant value?
      Parameters:
      optTable - The Optimizable that we want to know whether we are comparing to a known constant.
      considerParameters - Whether or not to consider parameters with defaults as known constants.
    • getCompareValue

      DataValueDescriptor getCompareValue(Optimizable optTable) throws StandardException
      Get an Object representing the known constant value that the given Optimizable is being compared to.
      Throws:
      StandardException - Thrown on error
    • equalsComparisonWithConstantExpression

      boolean equalsComparisonWithConstantExpression(Optimizable optTable)
      Is this predicate an equality comparison with a constant expression? (IS NULL is considered to be an = comparison with a constant expression).
      Parameters:
      optTable - The Optimizable for which we want to know whether it is being equality-compared to a constant expression.
    • hasEqualOnColumnList

      int hasEqualOnColumnList(int[] baseColumnPositions, Optimizable optTable) throws StandardException
      Returns if the predicate involves an equal operator on one of the columns specified in the baseColumnPositions.
      Parameters:
      baseColumnPositions - the column numbers on which the user wants to check if the equality condition exists.
      optTable - the table for which baseColumnPositions are given.
      Returns:
      returns the index into baseColumnPositions of the column that has the equality operator.
      Throws:
      StandardException
    • selectivity

      double selectivity(Optimizable optTable) throws StandardException
      Get a (crude) estimate of the selectivity of this predicate. This is to be used when no better technique is available for estimating the selectivity - this method's estimate is a hard- wired number based on the type of predicate and the datatype (the selectivity of boolean is always 50%).
      Parameters:
      optTable - The Optimizable that this predicate restricts
      Throws:
      StandardException
    • getIndexPosition

      int getIndexPosition()
      Get the position of the index column that this predicate restricts. NOTE: This assumes that this predicate is part of an OptimizablePredicateList, and that classify() has been called on the OptimizablePredicateList.
      Returns:
      The index position that this predicate restricts (zero-based)