From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Bruce Momjian <bruce@momjian.us>
Cc: Andres Freund <andres@anarazel.de>
Cc: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>
Cc: tsunakawa.takay@jp.fujitsu.com
Cc: robertmhaas@gmail.com
Cc: tgl@sss.pgh.pa.us
Cc: ideriha.takeshi@jp.fujitsu.com
Cc: pgsql-hackers@lists.postgresql.org
Cc: michael.paquier@gmail.com
Cc: david@pgmasters.net
Cc: craig@2ndquadrant.com
Subject: Re: Protect syscache from bloating with negative cache entries
Date: Mon, 18 Feb 2019 10:49:56 -0300
Message-ID: <20190218134956.GA909@alvherre.pgsql> (raw)
In-Reply-To: <b79b09bd-fa8f-8501-0781-fa4e3619bd54@2ndquadrant.com>
On 2019-Feb-15, Tomas Vondra wrote:
> ISTM there's a couple of ways to deal with that:
>
> 1) Ignore the memory amounts entirely, and do just time-base eviction.
>
> 2) If we want some size thresholds (e.g. to disable eviction for
> backends with small caches etc.) use the number of entries instead. I
> don't think that's particularly worse that specifying size in MB.
Why is there a *need* for size-based eviction? Seems that time-based
should be sufficient. Is the proposed approach to avoid eviction at all
until the size threshold has been reached? I'm not sure I see the point
of that.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-hackers@postgresql.org
Cc: alvherre@2ndquadrant.com, tomas.vondra@2ndquadrant.com, bruce@momjian.us, andres@anarazel.de, horiguchi.kyotaro@lab.ntt.co.jp, tsunakawa.takay@jp.fujitsu.com, robertmhaas@gmail.com, tgl@sss.pgh.pa.us, ideriha.takeshi@jp.fujitsu.com, pgsql-hackers@lists.postgresql.org, michael.paquier@gmail.com, david@pgmasters.net, craig@2ndquadrant.com
Subject: Re: Protect syscache from bloating with negative cache entries
In-Reply-To: <20190218134956.GA909@alvherre.pgsql>
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