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From: David Kerr <dmk@mr-paradox.net>
To: pgsql-performance@postgresql.org
Subject: Process 11812 still waiting for ExclusiveLock on extension of relation
Date: Tue, 17 Jul 2012 08:57:52 -0700
Message-ID: <20120717155752.GC38474@mr-paradox.net> (raw)

Howdy,

I've got a couple of tables that are taking a little longer than normal to extend, resulting 
in some slow inserts.

They're fairly large tables, ~200GB pg_total_relation_size (90GB for just the table)

I suspect that this is related to a sustained heavy load that would stop autovacuum from
getting at this table... Does that sound plausible? 

I'm wondering what options I have to smooth over these episodes / speed up the extensions.
I'm thinking of something like, CLUSTER or VACUUM FULL (those take quite a run so I'd like 
some direction on it before i TiaS =) )

I suspect that Partitioning would help.  Any other ideas?


Jul 17 08:11:52 perf: [3-1] user=test,db=perf LOG:  process 11812 still waiting for ExclusiveLock 
on extension of relation 60777 of database 16387 after 1000.270 ms

System resouces were fine:

PGDATA
------
07/17/12 08:11:48
Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
dm-2              1.20  3085.20   77.20 3994.20 15363.20 56680.00    17.69    15.57    3.82   0.06  26.22

07/17/12 08:11:53
Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
dm-2              0.40  2097.20   51.80 2610.20 10344.00 37659.20    18.03     5.23    1.96   0.05  14.28


PGXLOG
------
07/17/12 08:11:48
Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
dm-4              0.00  3958.20    0.00  600.40     0.00 36449.60    60.71     0.44    0.74   0.73  43.54

07/17/12 08:11:53
Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s avgrq-sz avgqu-sz   await  svctm  %util
dm-4              0.00  2905.20    0.00  403.40     0.00 26492.80    65.67     0.32    0.80   0.79  31.96

CPU
------
                CPU     %user     %nice   %system   %iowait    %steal     %idle
08:11:48        all     24.49      0.00      3.19      1.17      0.00     71.15
08:11:53        all     17.53      0.00      3.13      0.68      0.00     78.65




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