From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tobias Brox <tobixen@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: locking issue on simple selects?
Date: Wed, 15 Sep 2010 15:21:18 -0400
Message-ID: <23278.1284578478@sss.pgh.pa.us> (raw)
In-Reply-To: <AANLkTikzssP3AKeQhM+tB_8tScRGs2iGSqTJJUg2w3DP@mail.gmail.com>
References: <AANLkTikh++7mouBb7cr2C9zMPKtRffVxDK0QFTf16HLo@mail.gmail.com>
<4096.1284557987@sss.pgh.pa.us>
<AANLkTikzssP3AKeQhM+tB_8tScRGs2iGSqTJJUg2w3DP@mail.gmail.com>
Tobias Brox <tobixen@gmail.com> writes:
> Well - I thought so, we have a logging script that logs the content of
> the pg_locks table, it didn't log anything interesting but it may be a
> problem with the script itself. It does an inner join on
> pg_locks.relation = pg_class.oid but when I check now this join seems
> to remove most of the rows in the pg_locks table. Does it make sense
> at all to join pg_class with pg_locks? I will ask the sysadm to
> change to an outer join as for now.
There are lots of locks that are not tied to a specific table, so an
inner join is definitely bad. You could use an outer join to annotate
rows that do correspond to table locks, though.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, tobixen@gmail.com
Subject: Re: locking issue on simple selects?
In-Reply-To: <23278.1284578478@sss.pgh.pa.us>
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