Kyotaro,
Are you planning to update this patch based on Heikki's comments? The patch is listed in the commitfest and we're
tryingto make some progress through all of those patches.
Thanks,
Stephen
* Heikki Linnakangas (hlinnaka@iki.fi) wrote:
> On 12.11.2012 12:07, Kyotaro HORIGUCHI wrote:
> >Hello, This is new version of identity projection patch.
> >
> >Reverted projectionInfo and ExecBuildProjectionInfo. Identity
> >projection is recognized directly in ExecGroup, ExecResult, and
> >ExecWindowAgg. nodeAgg is reverted because I couldn't make it
> >sane..
> >
> >The following is the result of performance test posted before in
> >order to show the source of the gain.
>
> Hmm, this reminds me of the discussion on removing useless Limit
> nodes: http://archives.postgresql.org/pgsql-performance/2012-12/msg00127.php.
>
> The optimization on Group, WindowAgg and Agg nodes doesn't seem that
> important, the cost of doing the aggregation/grouping is likely
> overwhelming the projection cost, and usually you do projection in
> grouping/aggregation anyway. But makes sense for Result.
>
> For Result, I think you should aim to remove the useless Result node
> from the plan altogether. And do the same for useless Limit nodes.
>
> - Heikki
>