[jira] [Commented] (CALCITE-4189) Simplify 'P OR P IS NOT TRUE' to 'TRUE'

["Thomas Rebele (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17197045#comment-17197045 ] 

Thomas Rebele commented on CALCITE-4189:
----------------------------------------

A similar optimization is done for AND in 
* org.apache.calcite.rex.RexSimplify#simplifyAnd2 and 
* org.apache.calcite.rex.RexSimplify#simplifyAnd2ForUnknownAsFalse.

It might make sense to add a helper method and handle these three occurrences with the same code.

PS: I wonder why RexSimplify treats AND and OR differently, as AND and OR are dual to each other. A slightly generalized algorithm could deal with both at the same time.
 

> Simplify 'P OR P IS NOT TRUE' to 'TRUE'
> ---------------------------------------
>
>                 Key: CALCITE-4189
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4189
>             Project: Calcite
>          Issue Type: Improvement
>            Reporter: Thomas Rebele
>            Priority: Minor
>
> Statements of the form 'P OR P IS NOT TRUE' to 'TRUE' should always be true (please correct me if I am wrong):
> {code:java}
> > select x, X='A' as EQ, 
>             X='A' IS NOT TRUE as EQ_NOT_TRUE,
>             (X='A') OR ((X='A') IS NOT TRUE) as EQ_OR_EQ_NOT_TRUE
> from (values 'A', 'B', null) as t(x);
> +---+-------+-------------+-------------------+
> | X |  EQ   | EQ_NOT_TRUE | EQ_OR_EQ_NOT_TRUE |
> +---+-------+-------------+-------------------+
> | A | true  | false       | true              |
> | B | false | true        | true              |
> |   |       | true        | true              |
> +---+-------+-------------+-------------------+
> {code}
> Here a test case for the expected behavior:
> {code:java}
> @Test void testSimplifyPOrPNotTrue() {
>   checkSimplify(
>       and(
>           vBool(),
>           or(
>               eq(vInt(), literal(1)),
>               isNotTrue(eq(vInt(), literal(1)))
>           )),
>       "?0.bool0");
> }{code}
> There are some other, similar expressions, such as 'P IS NOT FALSE OR NOT P', which can be reduced to true. Maybe there's a way to handle all of them?



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