Package org.apache.beam.sdk.extensions.sql.impl.rel

Class CalcRelSplitter

java.lang.Object
org.apache.beam.sdk.extensions.sql.impl.rel.CalcRelSplitter
public class CalcRelSplitter extends Object
CalcRelSplitter operates on a Calc with multiple RexCall sub-expressions that cannot all be implemented by a single concrete RelNode.

This is a copy of CalcRelSplitter modified to work with Beam. TODO(CALCITE-4538) consider contributing these changes back upstream.

For example, the Java and Fennel calculator do not implement an identical set of operators. The Calc can be used to split a single Calc with mixed Java- and Fennel-only operators into a tree of Calc object that can each be individually implemented by either Java or Fennel.and splits it into several Calc instances.

Currently the splitter is only capable of handling two "rel types". That is, it can deal with Java vs. Fennel Calcs, but not Java vs. Fennel vs. some other type of Calc.

See

invalid reference 
ProjectToWindowRule
for an example of how this class is used.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    CalcRelSplitter.RelType
    Type of relational expression.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rex.RexProgram
    program
     
    protected final org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.tools.RelBuilder
    relBuilder
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    CalcRelSplitter(org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.core.Calc calc, org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.tools.RelBuilder relBuilder, CalcRelSplitter.RelType[] relTypes)
    Constructs a CalcRelSplitter.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected boolean
    canImplement(org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.logical.LogicalCalc rel, String relTypeName)
    Returns whether a relational expression can be implemented solely in a given CalcRelSplitter.RelType.
    org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.RelNode
    execute()
     
    protected List<Set<Integer>>
    getCohorts()
    Returns a list of sets of expressions that should be on the same level.
    protected org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.RelNode
    handle(org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.RelNode rel)
    Opportunity to further refine the relational expression created for a given level.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • program

      protected final org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rex.RexProgram program

    • relBuilder

      protected final org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.tools.RelBuilder relBuilder

  • Constructor Details

    • CalcRelSplitter

      public CalcRelSplitter(org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.core.Calc calc, org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.tools.RelBuilder relBuilder, CalcRelSplitter.RelType[] relTypes)
      Constructs a CalcRelSplitter.
      Parameters:
      calc - Calc to split
      relTypes - Array of rel types, e.g. {Java, Fennel}. Must be distinct.

  • Method Details

    • execute

      public org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.RelNode execute()

    • handle

      protected org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.RelNode handle(org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.RelNode rel)
      Opportunity to further refine the relational expression created for a given level. The default implementation returns the relational expression unchanged.

    • canImplement

      protected boolean canImplement(org.apache.beam.vendor.calcite.v1_28_0.org.apache.calcite.rel.logical.LogicalCalc rel, String relTypeName)
      Returns whether a relational expression can be implemented solely in a given CalcRelSplitter.RelType.
      Parameters:
      rel - Calculation relational expression
      relTypeName - Name of a CalcRelSplitter.RelType
      Returns:
      Whether relational expression can be implemented

    • getCohorts

      protected List<Set<Integer>> getCohorts()
      Returns a list of sets of expressions that should be on the same level.

      For example, if this method returns { {3, 5}, {4, 7} }, it means that expressions 3 and 5, should be on the same level, and expressions 4 and 7 should be on the same level. The two cohorts do not need to be on the same level.

      The list is best effort. If it is not possible to arrange that the expressions in a cohort are on the same level, the execute() method will still succeed.

      The default implementation of this method returns the empty list; expressions will be put on the most suitable level. This is generally the lowest possible level, except for literals, which are placed at the level where they are used.

      Returns:
      List of cohorts, that is sets of expressions, that the splitting algorithm should attempt to place on the same level