Subject: Re: Protect syscache from bloating with negative cache
 entries
To: pgsql-hackers@postgresql.org
References: 
 <CA+Tgmob_ksTOgmbXhno+k5XXPOK+-JYYLoU3MpXuutP4bH7gzA@mail.gmail.com>
 <CAMsr+YHziSok-AM=krEQ+HaRQzst4+M1+2WGYqZw_i6w9vVBvA@mail.gmail.com>
 <30868.1482246558@sss.pgh.pa.us>
 <CA+TgmoaMPbN5vvH33zLK7MR+PiCYWPvTHmSSrDab4vurLOXS-Q@mail.gmail.com>
 <23492.1482264621@sss.pgh.pa.us>
 <CAB7nPqQABjAGDzTREuHOgJS3iHY6nVZ+Z2x1cL1JLKBLMpzXTg@mail.gmail.com>
 <4647.1484315911@sss.pgh.pa.us>
 <CA+TgmobjDw_SWsxyJwT9z-YOwWv0ietuQx5fb=WEYdDfvCbzGQ@mail.gmail.com>
 <CAB7nPqRgkyR9p-Lz75no+Dz=t6FeHpXA68LU6-sevKhzdvgTjg@mail.gmail.com>
 <30626.1484348321@sss.pgh.pa.us>
 <20170113230631.uuq3ioq2qlyjio5q@alap3.anarazel.de>
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <c205fe42-1a02-92f4-5df3-fd469b95b89b@2ndquadrant.com>
Date: Sat, 14 Jan 2017 01:36:18 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <20170113230631.uuq3ioq2qlyjio5q@alap3.anarazel.de>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk
Sender: pgsql-hackers-owner@postgresql.org

On 01/14/2017 12:06 AM, Andres Freund wrote:
> Hi,
>
>
> On 2017-01-13 17:58:41 -0500, Tom Lane wrote:
>> But, again, the catcache isn't the only source of per-process bloat
>> and I'm not even sure it's the main one.  A more holistic approach
>> might be called for.
>
> It'd be helpful if we'd find a way to make it easy to get statistics
> about the size of various caches in production systems. Right now
> that's kinda hard, resulting in us having to make a lot of
> guesses...
>

What about a simple C extension, that could inspect those caches? 
Assuming it could be loaded into a single backend, that should be 
relatively acceptable way (compared to loading it to all backends using 
shared_preload_libraries).


-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


-- 
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers