| From: | David Rowley <dgrowleyml(at)gmail(dot)com> |
|---|---|
| To: | Melanie Plageman <melanieplageman(at)gmail(dot)com> |
| Cc: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org>, Andres Freund <andres(at)anarazel(dot)de>, Thomas Munro <thomas(dot)munro(at)gmail(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
| Subject: | Re: Streaming read-ready sequential scan code |
| Date: | 2024-01-29 21:24:36 |
| Message-ID: | CAApHDvrJMpHoiBKzts=26Yk8-DrTURNMXdKsku4fe39bKAeLrg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, 30 Jan 2024 at 10:17, Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
> Though logically the performance with 0001 and 0002 should be the same
> as master (no new non-inline function calls, no additional looping),
> I've done a bit of profiling anyway. I created a large multi-GB table,
> read it all into shared buffers (disabling the large sequential scan
> bulkread optimization), and did a sequential SELECT count(*) from the
> table. From the profiles below, you'll notice that master and the
> patch are basically the same. Actual percentages vary from run-to-run.
> Execution time is the same.
Can you also run a test on a Seqscan with a filter that filters out
all tuples? There's less overhead in other parts of the executor with
such a query.
David
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