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