com.hazelcast.org.apache.calcite.rel.core.JoinRelType Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.hazelcast.org.apache.calcite.rel.core;
import java.util.Locale;
/**
* Enumeration of join types.
*/
public enum JoinRelType {
/**
* Inner join.
*/
INNER,
/**
* Left-outer join.
*/
LEFT,
/**
* Right-outer join.
*/
RIGHT,
/**
* Full-outer join.
*/
FULL,
/**
* Semi-join.
*
* For example, {@code EMP semi-join DEPT} finds all {@code EMP} records
* that have a corresponding {@code DEPT} record:
*
*
* SELECT * FROM EMP
* WHERE EXISTS (SELECT 1 FROM DEPT
* WHERE DEPT.DEPTNO = EMP.DEPTNO)
*
*/
SEMI,
/**
* Anti-join (also known as Anti-semi-join).
*
* For example, {@code EMP anti-join DEPT} finds all {@code EMP} records
* that do not have a corresponding {@code DEPT} record:
*
*
* SELECT * FROM EMP
* WHERE NOT EXISTS (SELECT 1 FROM DEPT
* WHERE DEPT.DEPTNO = EMP.DEPTNO)
*
*/
ANTI;
/** Lower-case name. */
public final String lowerName = name().toLowerCase(Locale.ROOT);
/**
* Returns whether a join of this type may generate NULL values on the
* right-hand side.
*/
public boolean generatesNullsOnRight() {
return (this == LEFT) || (this == FULL);
}
/**
* Returns whether a join of this type may generate NULL values on the
* left-hand side.
*/
public boolean generatesNullsOnLeft() {
return (this == RIGHT) || (this == FULL);
}
/**
* Returns whether a join of this type is an outer join, returns true if the join type may
* generate NULL values, either on the left-hand side or right-hand side.
*/
public boolean isOuterJoin() {
return (this == LEFT) || (this == RIGHT) || (this == FULL);
}
/**
* Swaps left to right, and vice versa.
*/
public JoinRelType swap() {
switch (this) {
case LEFT:
return RIGHT;
case RIGHT:
return LEFT;
default:
return this;
}
}
/** Returns whether this join type generates nulls on side #{@code i}. */
public boolean generatesNullsOn(int i) {
switch (i) {
case 0:
return generatesNullsOnLeft();
case 1:
return generatesNullsOnRight();
default:
throw new IllegalArgumentException("invalid: " + i);
}
}
/** Returns a join type similar to this but that does not generate nulls on
* the left. */
public JoinRelType cancelNullsOnLeft() {
switch (this) {
case RIGHT:
return INNER;
case FULL:
return LEFT;
default:
return this;
}
}
/** Returns a join type similar to this but that does not generate nulls on
* the right. */
public JoinRelType cancelNullsOnRight() {
switch (this) {
case LEFT:
return INNER;
case FULL:
return RIGHT;
default:
return this;
}
}
public boolean projectsRight() {
return this != SEMI && this != ANTI;
}
}