com.hazelcast.org.apache.calcite.plan.DeriveMode Maven / Gradle / Ivy
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* (the "License"); you may not use this file except in compliance with
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*
* http://www.apache.org/licenses/LICENSE-2.0
*
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package com.hazelcast.org.apache.calcite.plan;
/**
* The mode of trait derivation.
*/
public enum DeriveMode {
/**
* Uses the left most child's traits to decide what
* traits to require from the other children. This
* generally applies to most operators.
*/
LEFT_FIRST,
/**
* Uses the right most child's traits to decide what
* traits to require from the other children. Operators
* like index nested loop join may find this useful.
*/
RIGHT_FIRST,
/**
* Iterates over each child, uses current child's traits
* to decide what traits to require from the other
* children. It includes both LEFT_FIRST and RIGHT_FIRST.
* System that doesn't enable join commutativity should
* consider this option. Special customized operators
* like a Join who has 3 inputs may find this useful too.
*/
BOTH,
/**
* Leave it to you, you decide what you cook. This will
* allow planner to pass all the traits from all the
* children, the user decides how to make use of these
* traits and whether to derive new rel nodes.
*/
OMAKASE,
/**
* Trait derivation is prohibited.
*/
PROHIBITED
}