io.prestosql.sql.planner.iterative.rule

Class UnwrapCastInComparison

java.lang.Object

io.prestosql.sql.planner.iterative.rule.ExpressionRewriteRuleSet

io.prestosql.sql.planner.iterative.rule.UnwrapCastInComparison

public class UnwrapCastInComparison
extends ExpressionRewriteRuleSet

Given s of type S, a constant expression t of type T, and when an implicit cast exists between S->T, converts expression of the form:

 CAST(s as T) = t
 

into

 s = CAST(t as S)
 

For example:

 CAST(x AS bigint) = bigint '1'

turns into

 x = smallint '1'
 

It can simplify expressions that are known to be true or false, and remove the comparisons altogether. For example, give x::smallint, for an expression like:

 CAST(x AS bigint) > bigint '10000000'

Nested Class Summary

Nested classes/interfaces inherited from class io.prestosql.sql.planner.iterative.rule.ExpressionRewriteRuleSet

ExpressionRewriteRuleSet.ExpressionRewriter

Constructor Summary

Constructors

Constructor and Description
UnwrapCastInComparison(Metadata metadata, TypeAnalyzer typeAnalyzer)

Method Summary

Methods inherited from class io.prestosql.sql.planner.iterative.rule.ExpressionRewriteRuleSet

aggregationExpressionRewrite, applyExpressionRewrite, filterExpressionRewrite, joinExpressionRewrite, projectExpressionRewrite, rules, valuesExpressionRewrite

Methods inherited from class java.lang.Object

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

Constructor Detail

UnwrapCastInComparison

public UnwrapCastInComparison(Metadata metadata,
                              TypeAnalyzer typeAnalyzer)