From: Rural Hunter <ruralhunter@gmail.com>
To: Bèrto ëd Sèra <berto.d.sera@gmail.com>
Cc: pgsql-admin@postgresql.org, Kevin Grittner <kevin.grittner@wicourts.gov>
Cc: Jerry Sievers <gsievers19@comcast.net>
Subject: Re: lock problem
Date: Thu, 22 Dec 2011 00:02:59 +0800
Message-ID: <4EF20333.8020404@gmail.com> (raw)
In-Reply-To: <CAKwGa__-7ncap5sji9x0=3g5V=Fv1cpZYGO5bKDHgxeT6z9rzg@mail.gmail.com>
References: <4EF18A8A0200002500043F0A@gw.wicourts.gov>
<CAKwGa_-C0Gcp2PaNWS9_kq0nz7KfcbV8hb5XYmxzUyHNt6AF-w@mail.gmail.com>
<4EF1F027.507@gmail.com>
<87aa6m7xqz.fsf@comcast.net>
<CAKwGa__-7ncap5sji9x0=3g5V=Fv1cpZYGO5bKDHgxeT6z9rzg@mail.gmail.com>
well, thanks. I checked the application and found there was a bug
causing many queries were updating the same row. However, those updates
are just single statement, no multi-statement transaction involved. So
I still have this question:
same statement A,B,C,D update same row. The start order is A->B->C-D.
From what I've gotten, B/C/D got the lock before A. Why did that
happen?
于2011年12月21日 23:40:35,Bèrto ëd Sèra写到:
> Hi,
>
> > I dig another case more and found something interesting. it's
> actually
> > waiting for a lock of type transactionid. I ran the query below 3
>
> Normal. That's the kind of lock you are waiting for when some other
> transaction has touched the same rows for update that you are
> attempting.
>
>
> Record level locks are stored on the records themselves, so you won't
> see them explicitly mentioned in views like pg_locks:
> "Although tuples are a lockable type of object, information about
> row-level locks is stored on disk, not in memory, and therefore
> row-level locks normally do not appear in this view. If a transaction
> is waiting for a row-level lock, it will usually appear in the view as
> waiting for the permanent transaction ID of the current holder of that
> row lock."
> See http://www.postgresql.org/docs/9.1/static/explicit-locking.html
>
> Bèrto
> --
> ==============================
> If Pac-Man had affected us as kids, we'd all be running around in a
> darkened room munching pills and listening to repetitive music.
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To: pgsql-admin@postgresql.org
Cc: ruralhunter@gmail.com, berto.d.sera@gmail.com, kevin.grittner@wicourts.gov, gsievers19@comcast.net
Subject: Re: lock problem
In-Reply-To: <4EF20333.8020404@gmail.com>
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