io.prestosql.sql.planner.iterative.rule

Class PushTopNThroughOuterJoin

java.lang.Object

io.prestosql.sql.planner.iterative.rule.PushTopNThroughOuterJoin

All Implemented Interfaces:

Rule<TopNNode>

public class PushTopNThroughOuterJoin
extends Object
implements Rule<TopNNode>

Transforms:

 - TopN (partial)
    - Join (left, right)
       - left source
       - right source
 

Into:

 - Join
    - TopN (present if Join is left, not already limited, and orderBy symbols come from left source)
       - left source
    - TopN (present if Join is right, not already limited, and orderBy symbols come from right source)
       - right source
 

TODO: this Rule violates the expectation that Rule transformations must preserve the semantics of the expression subtree. It works only because it's a PARTIAL TopN, so there will be a FINAL TopN that "fixes" it.

Nested Class Summary

Nested classes/interfaces inherited from interface io.prestosql.sql.planner.iterative.Rule

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor and Description
PushTopNThroughOuterJoin()

Method Summary

Modifier and Type	Method and Description
Rule.Result	apply(TopNNode parent, Captures captures, Rule.Context context)
Pattern<TopNNode>	getPattern() Returns a pattern to which plan nodes this rule applies.

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.prestosql.sql.planner.iterative.Rule

isEnabled

Constructor Detail

PushTopNThroughOuterJoin

public PushTopNThroughOuterJoin()

Method Detail

getPattern

public Pattern<TopNNode> getPattern()

Description copied from interface: Rule

Returns a pattern to which plan nodes this rule applies.

Specified by:

getPattern in interface Rule<TopNNode>

apply

public Rule.Result apply(TopNNode parent,
                         Captures captures,
                         Rule.Context context)

Specified by:

apply in interface Rule<TopNNode>