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 and 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 and 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 Detail

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