From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Masahiko Sawada <masahiko.sawada@2ndquadrant.com>
Cc: tsunakawa.takay@fujitsu.com <tsunakawa.takay@fujitsu.com>
Cc: pgsql-hackers@postgresql.org <pgsql-hackers@postgresql.org>
Subject: Re: SLRU statistics
Date: Sat, 29 Feb 2020 11:44:26 -0300
Message-ID: <20200229144426.GA32500@alvherre.pgsql> (raw)
In-Reply-To: <20200229122441.ow7gnnqgesmojyc3@development>
On 2020-Feb-29, Tomas Vondra wrote:
> Did we actually remove track-enabling GUCs? I think we still have
>
> - track_activities
> - track_counts
> - track_io_timing
> - track_functions
>
> But maybe I'm missing something?
Hm I remembered we removed the one for row-level stats
(track_row_stats), but what we really did is merge it with block-level
stats (track_block_stats) into track_counts -- commit 48f7e6439568.
Funnily enough, if you disable that autovacuum won't work, so I'm not
sure it's a very useful tunable. And it definitely has more overhead
than what this new GUC would have.
> > I find SlruType pretty odd, and the accompanying "if" list in
> > pg_stat_get_slru() correspondingly so. Would it be possible to have
> > each SLRU enumerate itself somehow? Maybe add the name in SlruCtlData
> > and query that, somehow. (I don't think we have an array of SlruCtlData
> > anywhere though, so this might be a useless idea.)
>
> Well, maybe. We could have a system to register SLRUs dynamically, but
> the trick here is that by having a fixed predefined number of SLRUs
> simplifies serialization in pgstat.c and so on. I don't think the "if"
> branches in pg_stat_get_slru() are particularly ugly, but maybe we could
> replace the enum with a registry of structs, something like rmgrlist.h.
> It seems like an overkill to me, though.
Yeah, maybe we don't have to fix that now.
--
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, masahiko.sawada@2ndquadrant.com, tsunakawa.takay@fujitsu.com
Subject: Re: SLRU statistics
In-Reply-To: <20200229144426.GA32500@alvherre.pgsql>
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