[jira] [Commented] (CALCITE-3167) Remove overriding equals and hashCode methods in EnumerableTableScan

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-3167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16877237#comment-16877237 ] 

Julian Hyde commented on CALCITE-3167:
--------------------------------------

I tend to agree that sub-classes of {{RelNode}} should not override {{equals}} and {{hashCode}}. There are other mechanisms to define identity, and no one mechanism is sufficient for all cases.

If so, we should override {{equals}} and {{hashCode}} in {{AbstractRelNode}} and make them final, to prevent other sub-classes from doing it.

These overrides were added in CALCITE-1216 by [~amargoor]. Have you analyzed that fix, and why the methods were needed? Were there sufficient tests in that fix to detect any regression you might be introducing here?

> Remove overriding equals and hashCode methods in EnumerableTableScan
> --------------------------------------------------------------------
>
>                 Key: CALCITE-3167
>                 URL: https://issues.apache.org/jira/browse/CALCITE-3167
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>    Affects Versions: 1.19.0
>            Reporter: jin xing
>            Priority: Minor
>              Labels: pull-request-available
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> In current code of {{EnumerableTableScan}}, methods of equals and hashCode are overridden for matching of {{EnumerableTableScan}}s.
> While after optimizing with the same HEP planner, {{EnumerableTableScan}}s from two plans but with the same digest will the share the same Java object. See [RelOptMaterializations|https://github.com/apache/calcite/blob/adf4cc4dc5cdb9f5e49c85d10f46a2fdcd831ccf/core/src/main/java/org/apache/calcite/plan/RelOptMaterializations.java#L192].
> I think it's ok to remove the redundant overriding methods in {{EnumerableTableScan}}.



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