Re: Prefetch the next tuple's memory during seqscans
| От | sirisha chamarthi |
|---|---|
| Тема | Re: Prefetch the next tuple's memory during seqscans |
| Дата | |
| Msg-id | CAKrAKeUQ_2bqmCxO6+dUjO+adrrcnZn-+Nz5O8ok0Yb2h=LS_w@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Prefetch the next tuple's memory during seqscans (David Rowley <dgrowleyml@gmail.com>) |
| Ответы |
Re: Prefetch the next tuple's memory during seqscans
|
| Список | pgsql-hackers |
On Tue, Nov 22, 2022 at 11:44 PM David Rowley <dgrowleyml@gmail.com> wrote:
On Wed, 23 Nov 2022 at 20:29, sirisha chamarthi
<sirichamarthi22@gmail.com> wrote:
> I ran your test1 exactly like your setup except the row count is 3000000 (with 13275 blocks). Shared_buffers is 128MB and the hardware configuration details at the bottom of the mail. It appears Master + 0001 + 0005 regressed compared to master slightly .
Thank you for running these tests.
Can you share if the plans used for these queries was a parallel plan?
I had set max_parallel_workers_per_gather to 0 to remove the
additional variability from parallel query.
Also, 13275 blocks is 104MBs, does EXPLAIN (ANALYZE, BUFFERS) indicate
that all pages were in shared buffers? I used pg_prewarm() to ensure
they were so that the runs were consistent.
I reran the test with setting max_parallel_workers_per_gather = 0 and with pg_prewarm. Appears I missed some step while testing on the master, thanks for sharing the details. New numbers show master has higher latency than Master + 0001 + 0005.
Master
Before vacuum:
latency average = 452.881 ms
Before vacuum:
latency average = 452.881 ms
After vacuum:
latency average = 393.880 ms
Master + 0001 + 0005
Before vacuum:
latency average = 441.832 ms
After vacuum:
latency average = 369.591 ms
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