Re: Update blocking a select count(*)?

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Benedict Holland" <benedict(dot)m(dot)holland(at)gmail(dot)com>
Cc: <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Update blocking a select count(*)?
Date: 2012-06-15 20:00:06
Message-ID: 4FDB4DF602000025000484FE@gw.wicourts.gov
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Benedict Holland <benedict(dot)m(dot)holland(at)gmail(dot)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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