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https://issues.apache.org/jira/browse/CALCITE-3167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16878107#comment-16878107
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Julian Hyde commented on CALCITE-3167:
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I disagree with your point 2. For some purposes, you might want two {{RelNode}}
instances to be equal if and only if their {{id}} fields are equal. For other
purposes, you might want two {{RelNode}} instances to be equal if and only if
their {{digest}} fields are equal. I think it is better that the people
designing those algorithms are explicit about how they define equality, and use
maps based on particular fields to achieve the behavior they want.
I agree on your other points. If we are accidentally breaking CALCITE-1216 with
this change, I trust its authors to speak up; we've done our best, because we
have run the tests they provided.
> 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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