[jira] [Commented] (CALCITE-4331) RelOptUtil#areRowTypesEqual should compare type nullability even for ANY types

["Vladimir Sitnikov (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-4331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17212264#comment-17212264 ] 

Vladimir Sitnikov commented on CALCITE-4331:
--------------------------------------------

Just for the reference, the added {{isNullable()}} check triggers no new failures in CI.

> RelOptUtil#areRowTypesEqual should compare type nullability even for ANY types
> ------------------------------------------------------------------------------
>
>                 Key: CALCITE-4331
>                 URL: https://issues.apache.org/jira/browse/CALCITE-4331
>             Project: Calcite
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 1.26.0
>            Reporter: Vladimir Sitnikov
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Calcite ignores data types completely if one of them is {{SqlTypeName.ANY}}.
> That enables to transform rowtype from {{name ANY NON NULL}} to {{name ANY NULLABLE}} in a planner rule, even though, the planner typically does not allow to loosen field nullability (e.g. transform from {{CHARACTER NON NULL}} to {{CHARACTER NULLABLE}} typically fails with rel {{rowtype...equivRel rowtype}} assertion error).
> What I got was silent wrong results {{count(name)}} was transformed to {{count(\*)}} since Calcite believed the field was non-nullable, and it did not care that I provided nullable rex for the implementation. Frankly speaking, I assumed "no asserts => the rowtypes in call.transformTo(..) are ok"
> Current code:
> {code:java}
>     for (Pair<RelDataTypeField, RelDataTypeField> pair : Pair.zip(f1, f2)) {
>       final RelDataType type1 = pair.left.getType();
>       final RelDataType type2 = pair.right.getType();
>       // If one of the types is ANY comparison should succeed
>       if (type1.getSqlTypeName() == SqlTypeName.ANY
>           || type2.getSqlTypeName() == SqlTypeName.ANY) {
>         continue;
>       }
>       if (!type1.equals(type2)) {
>         return false;
>       }
> {code}
> I'm inclined add a check that both types have the same {{isNullable()}} value.
> ANY checks were added in https://github.com/apache/calcite/commit/5562fc3952f61d943f109796c3d62b7390a8ac48
> [~jacques], [~julianhyde], do you know if it is OK to add the following?
> {code:java}
> if (type1.isNullable() != type2.isNullable()) {
>   return false;
> }
> {code}



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