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

Class RemoveEmptyExceptBranches

java.lang.Object

io.trino.sql.planner.iterative.rule.RemoveEmptyExceptBranches

All Implemented Interfaces:

Rule<ExceptNode>

public class RemoveEmptyExceptBranches
extends Object
implements Rule<ExceptNode>

Removes branches from an ExceptNode that are guaranteed to produce 0 rows. A EXCEPT E1 EXCEPT E2 ... EXCEPT En is equivalent to A - (E1 + ... + En). If any of the Ei sets is empty, it can be removed. If only A is left and it's empty, it gets replaced with an empty Values node. Otherwise:

a projection to preserve the outputs symbols, in the case of EXCEPT ALL.

an aggregation to remove duplicates, in case of EXCEPT DISTINCT

Nested Class Summary

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

Rule.Context, Rule.Result

Constructor Summary

Constructors

Constructor	Description
RemoveEmptyExceptBranches()

Method Summary

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

RemoveEmptyExceptBranches

public RemoveEmptyExceptBranches()

Method Details

getPattern

public Pattern<ExceptNode> getPattern()

Description copied from interface: Rule

Returns a pattern to which plan nodes this rule applies.

Specified by:

getPattern in interface Rule<ExceptNode>

apply

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

Specified by:

apply in interface Rule<ExceptNode>