org.apache.calcite.plan

Class RexImplicationChecker

java.lang.Object

org.apache.calcite.plan.RexImplicationChecker

public class RexImplicationChecker
extends Object

Checks whether one condition logically implies another.

If A ⇒ B, whenever A is true, B will be true also.

For example:

• (x > 10) ⇒ (x > 5)
• (x = 10) ⇒ (x < 30 OR y > 30)
• (x = 10) ⇒ (x IS NOT NULL)
• (x > 10 AND y = 20) ⇒ (x > 5)

Constructor Summary

Constructors

Constructor and Description
RexImplicationChecker(RexBuilder builder, RexExecutor executor, RelDataType rowType)

Method Summary

Modifier and Type	Method and Description
boolean	implies(RexNode first, RexNode second) Checks if condition first implies (⇒) condition second.

Methods inherited from class java.lang.Object

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

Constructor Detail

RexImplicationChecker

public RexImplicationChecker(RexBuilder builder,
                             RexExecutor executor,
                             RelDataType rowType)

Method Detail

implies

public boolean implies(RexNode first,
                       RexNode second)

Checks if condition first implies (⇒) condition second.

This reduces to SAT problem which is NP-Complete. When this method says first implies second then it is definitely true. But it cannot prove that first does not imply second.

Parameters:

first - first condition

second - second condition

Returns:

true if it can prove first ⇒ second; otherwise false i.e., it doesn't know if implication holds