Package org.apache.flink.table.planner.plan.rules.logical

Class SubQueryDecorrelator

java.lang.Object
org.apache.calcite.rel.RelShuttleImpl
org.apache.flink.table.planner.plan.rules.logical.SubQueryDecorrelator
All Implemented Interfaces:
org.apache.calcite.rel.RelShuttle
public class SubQueryDecorrelator extends org.apache.calcite.rel.RelShuttleImpl
SubQueryDecorrelator finds all correlated expressions in a SubQuery, and gets an equivalent non-correlated relational expression tree and correlation conditions.

The Basic idea of SubQueryDecorrelator is from RelDecorrelator, however there are differences between them: 1. This class works with RexSubQuery, while RelDecorrelator works with LogicalCorrelate. 2. This class will get an equivalent non-correlated expressions tree and correlation conditions, while RelDecorrelator will replace all correlated expressions with non-correlated expressions that are produced from joining the RelNode. 3. This class supports both equi and non-equi correlation conditions, while RelDecorrelator only supports equi correlation conditions.

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static class 
    SubQueryDecorrelator.Result
    Result describing the relational expression after decorrelation and where to find the equivalent non-correlated expressions and correlated conditions.
    static class 
    SubQueryDecorrelator.SubQueryRelDecorrelator
    Pull out all correlation conditions from a given subquery to top level, and rebuild the subquery rel tree without correlation conditions.

  • Field Summary

    Fields inherited from class org.apache.calcite.rel.RelShuttleImpl

    stack

  • Method Summary

    Modifier and Type
    Method
    Description
    static SubQueryDecorrelator.Result
    decorrelateQuery(org.apache.calcite.rel.RelNode rootRel)
    Decorrelates a subquery.
    org.apache.calcite.rel.RelNode
    visit(org.apache.calcite.rel.logical.LogicalFilter filter)
     
    protected org.apache.calcite.rel.RelNode
    visitChild(org.apache.calcite.rel.RelNode parent, int i, org.apache.calcite.rel.RelNode input)
     

    Methods inherited from class org.apache.calcite.rel.RelShuttleImpl

    visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visitChildren

    Methods inherited from class java.lang.Object

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

  • Method Details

    • decorrelateQuery

      public static SubQueryDecorrelator.Result decorrelateQuery(org.apache.calcite.rel.RelNode rootRel)
      Decorrelates a subquery.

      This is the main entry point to SubQueryDecorrelator.

      Parameters:
      rootRel - The node which has SubQuery.
      Returns:
      Decorrelate result.

    • visitChild

      protected org.apache.calcite.rel.RelNode visitChild(org.apache.calcite.rel.RelNode parent, int i, org.apache.calcite.rel.RelNode input)
      Overrides:
      visitChild in class org.apache.calcite.rel.RelShuttleImpl

    • visit

      public org.apache.calcite.rel.RelNode visit(org.apache.calcite.rel.logical.LogicalFilter filter)
      Specified by:
      visit in interface org.apache.calcite.rel.RelShuttle
      Overrides:
      visit in class org.apache.calcite.rel.RelShuttleImpl