Package io.trino.sql.planner.iterative.rule

Class ExtractDereferencesFromFilterAboveScan

java.lang.Object

io.trino.sql.planner.iterative.rule.ExtractDereferencesFromFilterAboveScan

All Implemented Interfaces:

Rule<FilterNode>

public class ExtractDereferencesFromFilterAboveScan
extends Object
implements Rule<FilterNode>

Transforms:

      Filter(f1(A.x.y) = 1 AND f2(B.m) = 2 AND f3(A.x) = 6)
          Source(A, B, C)
  

to:

  Project(A, B, C)
      Filter(f1(D) = 1 AND f2(E) = 2 AND f3(G) = 6)
          Project(A, B, C, D := A.x.y, E := B.m, G := A.x)
              Source(A, B, C)
 

This optimizer extracts all dereference expressions from a filter node located above a table scan into a ProjectNode.

Extracting dereferences from a filter (eg. FilterNode(a.x = 5)) can be suboptimal if full columns are being accessed up the plan tree (eg. a), because it can result in replicated shuffling of fields (eg. a.x). So it is safer to pushdown dereferences from Filter only when there's an explicit projection on top of the filter node (Ref PushDereferencesThroughFilter).

In case of a FilterNode on top of TableScanNode, we want to push all dereferences into a new ProjectNode below, so that PushProjectionIntoTableScan optimizer can push those columns in the connector, and provide new column handles for the projected subcolumns. PushPredicateIntoTableScan optimizer can then push predicates on these subcolumns into the connector.

Nested Class Summary

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

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor	Description
ExtractDereferencesFromFilterAboveScan(TypeAnalyzer typeAnalyzer)

Method Summary

Modifier and Type	Method	Description
Rule.Result	apply(FilterNode node, Captures captures, Rule.Context context)
Pattern<FilterNode>	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.trino.sql.planner.iterative.Rule

isEnabled

Constructor Detail

ExtractDereferencesFromFilterAboveScan

public ExtractDereferencesFromFilterAboveScan(TypeAnalyzer typeAnalyzer)

Method Detail

getPattern

public Pattern<FilterNode> getPattern()

Description copied from interface: Rule

Returns a pattern to which plan nodes this rule applies.

Specified by:

getPattern in interface Rule<FilterNode>

apply

public Rule.Result apply(FilterNode node,
                         Captures captures,
                         Rule.Context context)

Specified by:

apply in interface Rule<FilterNode>