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From: Kevin Grittner <Kevin.Grittner@wicourts.gov>
To: Benedict Holland <benedict.m.holland@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Update blocking a select count(*)?
Date: Fri, 15 Jun 2012 15:00:06 -0500
Message-ID: <4FDB4DF602000025000484FE@gw.wicourts.gov> (raw)
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Benedict Holland <benedict.m.holland@gmail.com> wrote:
 
> Is it a bug that the blocking process reported is the finial
> process but really the process blocking the intermediate?
 
What reported that?  The PostgreSQL server doesn't report such
things directly, and I don't know pgadmin, so I don't know about
that tool.  I wrote the recursive query on this page:
 
http://wiki.postgresql.org/wiki/Lock_dependency_information
 
So if that reported anything incorrecly, please let me know so I can
fix it.
 
By the way, the example with the three connections would have been
better had I suggested a BEGIN TRANSACTION ISOLATION LEVEL
REPEATABLE READ; on the third connection.  With that, even if one or
both of the transactions on the other connections committed, the
third transaction's count should remain unchanged.
 
-Kevin



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