On Mon, Jan 20, 2020 at 01:04:33AM +0000, tsunakawa.ta...@fujitsu.com wrote:
From: Tomas Vondra <tomas.von...@2ndquadrant.com>
One of the stats I occasionally wanted to know are stats for the SLRU
stats (we have couple of those - clog, subtrans, ...). So here is a WIP
version of a patch adding that.
How can users take advantage of this information? I think we also need
the ability to set the size of SLRU buffers. (I want to be freed from
the concern about the buffer shortage by setting the buffer size to its
maximum. For example, CLOG would be only 1 GB.)
You're right the users can't really take advantage of this - my primary
motivation was providing a feedback for devs, benchmarking etc. That
might have been done with DEBUG messages or something, but this seems
more convenient.
I think it's unclear how desirable / necessary it is to allow users to
tweak those caches. I don't think we should have a GUC for everything,
but maybe there's some sort of heuristics to determine the size. The
assumption is we actually find practical workloads where the size of
these SLRUs is a performance issue.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
