| From: | Claudio Freire <klaussfreire(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>, Aleksander Alekseev <a(dot)alekseev(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [Patch] Temporary tables that do not bloat pg_catalog (a.k.a fast temp tables) |
| Date: | 2016-08-23 22:33:33 |
| Message-ID: | CAGTBQpYisWL8i2bbTgW5uuJN+GhaCGJqE+3ud-BisF3DDVfhDw@mail.gmail.com |
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On Tue, Aug 23, 2016 at 7:20 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> Wouldn't more aggressive vacuuming of catalog tables fix the bloat?
>
> Not really in my experience, at least not without more drastic vacuum
> changes. The issue is that if you have a single "long running"
> transaction (in some workloads that can even just be a 3 min taking
> query/xact), nothing will be cleaned up during that time. If you have a
> few hundred temp tables created per sec, you'll be in trouble even
> then. Not to speak of the case where you have queries taking hours (say
> a backup).
Well, my experience isn't as extreme as that (just a few dozen temp
tables per minute), but when I see bloat in catalog tables it's
because all autovacuum workers are stuck vacuuming huge tables for
huge periods of time (hours or days).
So that's certainly another bloat case to consider.
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