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RE: Query is slow when run for first time; subsequent execution is fast - Mailing list pgsql-performance

From Nandakumar M
Subject RE: Query is slow when run for first time; subsequent execution is fast
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Msg-id CANcFUu52cPxGgr=mPpbgq5vQRv-VuadSSDpdf=PCbTnr2ndQ8g@mail.gmail.com
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In response to RE: Query is slow when run for first time; subsequent execution isfast  ("POUSSEL, Guillaume" <guillaume.poussel@sogeti.com>)
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Hi,

On 17 Jan 2018 12:55, "POUSSEL, Guillaume" <guillaume.poussel@sogeti.com> wrote:

Are you on Windows or Linux? I’m on Windows and wondering if the issue is the same on Linux?


I have experienced this on Mac and Linux machines.

You can try pg_prewarm, on pg_statistic table and its index.  But I'd probably just put an entry in my db startup script to run this query immediately after startng the server, and let the query warm the cache itself.

I will try this suggestion and get back on the thread. Is pg_statistic the only table to be pre cached? Pls let me know if any other table/index needs to be pre warmed.

Btw, I don't running a "select * from pg_statistic" will fill the shared buffer. Only 256 kb of data will be cached during sequential scans. I will try pg_prewarm

Why do you restart your database often

Postgres is bundled with our application and deployed by our client. Starting / stopping the server is not under my control.

Regards,
Nanda

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