io.prestosql.sql.planner.iterative.rule

Class TransformCorrelatedScalarSubquery

java.lang.Object

io.prestosql.sql.planner.iterative.rule.TransformCorrelatedScalarSubquery

All Implemented Interfaces:

Rule<LateralJoinNode>

public class TransformCorrelatedScalarSubquery
extends Object
implements Rule<LateralJoinNode>

Scalar filter scan query is something like:

     SELECT a,b,c FROM rel WHERE a = correlated1 AND b = correlated2
 

This optimizer can rewrite to mark distinct and filter over a left outer join:

From:

 - LateralJoin (with correlation list: [C])
   - (input) plan which produces symbols: [A, B, C]
   - (scalar subquery) Project F
     - Filter(D = C AND E > 5)
       - plan which produces symbols: [D, E, F]
 

to:

 - Filter(CASE isDistinct WHEN true THEN true ELSE fail('Scalar sub-query has returned multiple rows'))
   - MarkDistinct(isDistinct)
     - LateralJoin (with correlation list: [C])
       - AssignUniqueId(adds symbol U)
         - (input) plan which produces symbols: [A, B, C]
       - non scalar subquery
 

This must be run after TransformCorrelatedScalarAggregationToJoin

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
TransformCorrelatedScalarSubquery()

Method Summary

Modifier and Type	Method and Description
Rule.Result	apply(LateralJoinNode lateralJoinNode, Captures captures, Rule.Context context)
Pattern	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

TransformCorrelatedScalarSubquery

public TransformCorrelatedScalarSubquery()

Method Detail

getPattern

public Pattern getPattern()

Description copied from interface: Rule

Returns a pattern to which plan nodes this rule applies.

Specified by:

getPattern in interface Rule<LateralJoinNode>

apply

public Rule.Result apply(LateralJoinNode lateralJoinNode,
                         Captures captures,
                         Rule.Context context)

Specified by:

apply in interface Rule<LateralJoinNode>