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https://issues.apache.org/jira/browse/CALCITE-4557?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17326130#comment-17326130
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Julian Hyde commented on CALCITE-4557:
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{quote}I don't think it is necessary to simplify{quote}
It depends on the implementation. If your algorithm stores the sort keys
separately from the rows being sorted, it definitely makes a difference. And if
the cost model were to count the number of fields in the sort key, it would
make a difference to the cost model.
> Sort costing should account the number of sort keys: the more keys to
> compare, the more the cost
> ------------------------------------------------------------------------------------------------
>
> Key: CALCITE-4557
> URL: https://issues.apache.org/jira/browse/CALCITE-4557
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.26.0
> Reporter: Vladimir Sitnikov
> Priority: Major
>
> Current costing for sort does not account for the number of keys in the
> comparison function which might result in worse plan selection.
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