[jira] [Comment Edited] (CALCITE-4507) 'a = 0 or a is null' should not be rewrite to a sarg 'a in (0, null)'

["Danny Chen (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4507?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17288906#comment-17288906 ] 

Danny Chen edited comment on CALCITE-4507 at 2/23/21, 7:20 AM:
---------------------------------------------------------------

For the example in CALCITE-4446:

{{Sarg(10, 20, UNKNOWN AS UNKNOWN): x IN (10, 20) → UNKNOWN}}

then, what does {{x IN (10, null)}} return if x is null ? In mysql, it returns null (which i guess comes form an {{UNKNOWN}}). So mysql assumes {{x IN (10, null)}} returns {{UNKNOWN}} when x is null.

The question here is that {{IN}} compares the values using *EQUALS*, it is different with *x is NULL* statement, so i think this case is a little different, which is not a duplicate of CALCITE-4446.

{{x = 0 or x is null}} can never be rewritten to {{x IN(0, null)}} no matter what {{UNKNOWN AS}} value we have.


was (Author: danny0405):
For the example in CALCITE-4446:

{{Sarg(10, 20, UNKNOWN AS UNKNOWN): x IN (10, 20) → UNKNOWN}}

then, what does {{x IN (10, null)}} returns if x is null ? In mysql, it returns null (which i guess comes form an {{UNKNOWN}}). So mysql assumes {{x IN (10, null)}} returns {{UNKNOWN}} when x is null.

The question here is that {{IN}} compares the values using *EQUALS*, it is different with *x is NULL* statement, so i think this case is a little different, which is not a duplicate of CALCITE-4446.

{{x = 0 or x is null}} can never be written to {{x IN(0, null)}} no matter what {{UNKNOWN AS}} value we have.

> 'a = 0 or a is null' should not be rewrite to a sarg 'a in (0, null)'
> ---------------------------------------------------------------------
>
>                 Key: CALCITE-4507
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4507
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.26.0
>            Reporter: Danny Chen
>            Priority: Major
>
> SQL statements:
> {code:sql}
> a = 0 or a is null -- returns true when a is null
> a in (0, null) -- returns null when a is null
> {code}
> have different semantics when {{a}} is null, we should not represent it as a sarg after {{RexSimplify}},
> check this test in {{RexProgramTest}}:
> {code:java}
> @Test void testSimplifyInOr() {
>         or(
>             gt(vInt(), literal(0)),
>             isNull(vInt())),
>         ">(?0.int0, 0)");
>   }
> {code}



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