RE: Query is slow when run for first time; subsequent execution is fast

From: jimmy <mpokky(at)126(dot)com>
To: m(dot)nanda92(at)gmail(dot)com, pgsql-performance(at)postgresql(dot)org, guillaume(dot)poussel(at)sogeti(dot)com
Cc: jeff(dot)janes(at)gmail(dot)com
Subject: RE: Query is slow when run for first time; subsequent execution is fast
Date: 2018-09-04 07:16:10
Message-ID: 261af533.7aa3.165a3704c8b.Coremail.mpokky@126.com
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On windows, how to put an entry in my db startup script to run this query (pg_prewarm) immediately after startng the server, and let the query warm the cache itself.
After starting the server, I want to know what is the server, and it is the database I restarted or windows system?
Thank you.

>Hi,
>On 17 Jan 2018 12:55, "POUSSEL, Guillaume" <guillaume(dot)poussel(at)sogeti(dot)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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