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https://issues.apache.org/jira/browse/CALCITE-4558?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17310308#comment-17310308
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Julian Hyde commented on CALCITE-4558:
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Can you change the subject from 'Sort' to 'EnumerableSort'? Your comments only
apply to in-memory sorts that work by swapping pointers. I don't think we know
what is the cost model of these kinds of algorithm. We shouldn't assume that
accessing pointers is instantaneous - there will be a wait while they are
copied from RAM into cache - so the CPU cost is probably proportional to the
number of cells (field values) accessed during the sort.
> Sort CPU cost should not incur per-field copy cost for alignment with filter
> and project
> ----------------------------------------------------------------------------------------
>
> Key: CALCITE-4558
> URL: https://issues.apache.org/jira/browse/CALCITE-4558
> Project: Calcite
> Issue Type: Improvement
> Components: core
> Affects Versions: 1.26.0
> Reporter: Vladimir Sitnikov
> Priority: Major
>
> Typical Java implementations of the sort do not copy rows (they copy
> references only), so
> it makes little sense to have "row width" as the key driver of the sort
> costing.
> The CPU cost for filter does not include "row copy" cost.
> Even though the implementations might be different, in-core costs should be
> aligned.
> For instance, the current, EnumerableLimitSort and EnumerableSort have
> bytesPerRow multiplier, however, the implementation does not copy rows
> field-by-field .
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