Re: Help in avoiding a query 'Warm-Up' period/shared buffer cache

From: Qingqing Zhou
Subject: Re: Help in avoiding a query 'Warm-Up' period/shared buffer cache
Date: ,
Msg-id: dpkms7$1van$1@news.hub.org
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In response to: Help in avoiding a query 'Warm-Up' period/shared buffer cache  (Mark Liberman)
List: pgsql-performance


"Mark Liberman" <> wrote
>
> Now, my follow-up question / assumption.  I am assuming that the  IO time
> is
> so long on that index because it has to read the entire index (for that
> file_id) into memory
>
> any confirmation / corrections to my assumptions are greatly appreciated.
> E.g. is
> the compound index the way to go, or the solo index on file_id?
>

Only part of the index file is read. It is a btree index. Keep the index
smaller but sufficient to guide your search is always good because even by
the guidiance of the index, a heap visit to get the real data is not
avoidable.

Regards,
Qingqing




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