From: Richard Huxton <dev@archonet.com>
To: Kurt Overberg <kurt@hotdogrecords.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Maintenance question / DB size anomaly...
Date: Tue, 19 Jun 2007 18:04:50 +0100
Message-ID: <46780CB2.4070701@archonet.com> (raw)
In-Reply-To: <B79F5693-AD32-4254-8768-059E911D2703@hotdogrecords.com>
References: <A6D35557-74A3-47CF-B426-143C8CE01A13@hotdogrecords.com>
<4677E48A.9000007@archonet.com>
<B79F5693-AD32-4254-8768-059E911D2703@hotdogrecords.com>
Kurt Overberg wrote:
> Richard,
>
> Thanks for the feedback! I found oid2name and have been mucking about
> with it, but haven't really found anything that stands out yet. Most of
> the tables/indexes I'm comparing across machines seem to take up a
> similar amount of disk space. I think I'm going to have to get fancy
> and write some shell scripts. Regarding the slony configuration
> scripts, you're assuming that I have such scripts. Our slony install
> was originally installed by a contractor, and modified since then so
> "getting my act together with respect to slony" is kinda beyond the
> scope of what I'm trying to accomplish with this maintenance. I really
> just want to figure out whats going on with db1, and want to do so in a
> way that won't ruin slony since right now it runs pretty well, and I
> doubt I'd be able to fix it if it seriously broke.
>
> Upon a cursory pass with oid2name, it seems that my sl_log_1_idx1 index
> is out of hand:
If the sl_log_1 table is large too, it'll be worth reading throught the
FAQ to see if any of its notes apply.
http://cbbrowne.com/info/faq.html> -bash-3.00$ oid2name -d mydb -f 955960160
> From database "mydb":
> Filenode Table Name
> --------------------------
> 955960160 sl_log_1_idx1
>
> -bash-3.00$ ls -al 955960160*
> -rw------- 1 postgres postgres 1073741824 Jun 19 11:08 955960160
> -rw------- 1 postgres postgres 1073741824 Jun 13 2006 955960160.1
> -rw------- 1 postgres postgres 909844480 Jun 19 10:47 955960160.10
> -rw------- 1 postgres postgres 1073741824 Jul 31 2006 955960160.2
> -rw------- 1 postgres postgres 1073741824 Sep 12 2006 955960160.3
> -rw------- 1 postgres postgres 1073741824 Oct 19 2006 955960160.4
> -rw------- 1 postgres postgres 1073741824 Nov 27 2006 955960160.5
> -rw------- 1 postgres postgres 1073741824 Feb 3 12:57 955960160.6
> -rw------- 1 postgres postgres 1073741824 Mar 2 11:57 955960160.7
> -rw------- 1 postgres postgres 1073741824 Mar 29 09:46 955960160.8
> -rw------- 1 postgres postgres 1073741824 Mar 29 09:46 955960160.9
>
>
> I know that slony runs its vacuuming in the background, but it doesn't
> seem to be cleaning this stuff up. Interestingly, from my VACUUM
> pgfouine output,
> that index doesn't take that long at all to vacuum analyze (compared to
> my other, much larger tables). Am I making the OID->filename
> translation properly?
Looks OK to me
> Running this:
> SELECT relname, relpages FROM pg_class ORDER BY relpages DESC;
> ...gives me...
>
> sl_log_1_idx1 | 1421785
> xrefmembergroup | 1023460
> answerselectinstance | 565343
>
> ...does this jibe with what I'm seeing above? I guess I'll run a full
> vacuum on the slony tables too? I figured something would else would
> jump out bigger than this. FWIW, the same table on db2 and db3 is very
> small, like zero. I guess this is looking like it is overhead from
> slony? Should I take this problem over to the slony group?
Well, pages are 8KB each (by default), so that'd be about 10.8GB, which
seems to match your filesizes above.
Read through the FAQ I linked to - for some reason Slony's not clearing
out transactions it's replicated to your slaves (they *are* in sync,
aren't they?). Could be a transaction preventing vacuuming, or perhaps a
partially dropped node?
Check the size of the sl_log_1 table and see if that tallies.
--
Richard Huxton
Archonet Ltd
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Cc: dev@archonet.com, kurt@hotdogrecords.com
Subject: Re: Maintenance question / DB size anomaly...
In-Reply-To: <46780CB2.4070701@archonet.com>
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