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https://issues.apache.org/jira/browse/CALCITE-4189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17760131#comment-17760131
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Julian Hyde commented on CALCITE-4189:
--------------------------------------

No, I think we should do this rewrite the traditional way.

Simplifications by exhaustively iterating possible values (booleans, or numbers 
constrained by sargs) should be a separate jira case.

> 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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