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

Class PushDownProjectionsFromPatternRecognition

java.lang.Object

io.trino.sql.planner.iterative.rule.PushDownProjectionsFromPatternRecognition

All Implemented Interfaces:

Rule<PatternRecognitionNode>

public class PushDownProjectionsFromPatternRecognition
extends Object
implements Rule<PatternRecognitionNode>

Aggregate functions in pattern recognition context have special semantics. It is allowed to use `CLASSIFIER()` and `MATCH_NUMBER()` functions in aggregations arguments. Those calls are evaluated at runtime, as they depend on the pattern matching state.

As a consequence, some aggregation arguments cannot be pre-projected and replaced with single symbols. These are the "runtime-evaluated arguments".

The purpose of this rule is to identify and pre-project all arguments which are not runtime-evaluated.

Example: `array_agg(CLASSIFIER(A))` -> the argument `CLASSIFIER(A)` cannot be pre-projected `avg(A.price + A.tax)` -> we can pre-project the expression `price + tax`, and replace the argument with a single symbol. The label 'A', which prefixes column references, has been already extracted from the expression in the LogicalIndexExtractor.

Nested Class Summary

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

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor	Description
PushDownProjectionsFromPatternRecognition()

Method Summary

Modifier and Type	Method	Description
Rule.Result	apply(PatternRecognitionNode node, Captures captures, Rule.Context context)
Pattern<PatternRecognitionNode>	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

PushDownProjectionsFromPatternRecognition

public PushDownProjectionsFromPatternRecognition()

Method Detail

getPattern

public Pattern<PatternRecognitionNode> getPattern()

Description copied from interface: Rule

Returns a pattern to which plan nodes this rule applies.

Specified by:

getPattern in interface Rule<PatternRecognitionNode>

apply

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

Specified by:

apply in interface Rule<PatternRecognitionNode>