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Message-ID: <55c095e90702121127rf7daaebodf2efe1a5e1d2dcd@mail.gmail.com>
Date: Mon, 12 Feb 2007 16:27:15 -0300
From: "Ezequias Rodrigues da Rocha" <ezequias.rocha@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: [ADMIN] Deadlock on transaction
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Ok you teach me. Thank you and sorry. :(

I just want to know why is it occuring. I am pretty sad.

Ezequias

2007/2/12, Reinoud van Leeuwen <reinoud.v@n.leeuwen.net>:
>
> On Mon, Feb 12, 2007 at 03:08:27PM -0300, Ezequias Rodrigues da Rocha
> wrote:
> > I mean really deadlock. Other transactions can't access the database
> until
> > the main transaction is complete.
>
> What you describe sounds like a blocking lock: one transaction uses a
> resource and another has to wait until it is not locked anymore
>
> A deadlock is a special case: two transactions both need resources A and
> B. transaction 1 locks A, and the next moment transaction 2 locks B. Now
> transaction 1 waits for 2 to release B, but at the same time 2 waits for 1
> to release A. This is called a deadlock, or circulair lock.
> Postgresql automatically detects such a situation and rolls one of them
> back. The client recieves a 'restartable database error' and that is
> exactly true: ususally another try will work.
>
> One method of fixing deadlocks is to make sure all your code accesses the
> database in the same order. Alphabetically is easiest to remember...
>

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Ok you teach me. Thank you and sorry. :(<br><br>I just want to know why is it occuring. I am pretty sad.<br><br>Ezequias<br><br><div><span class="gmail_quote">2007/2/12, Reinoud van Leeuwen &lt;<a href="mailto:reinoud.v@n.leeuwen.net">
reinoud.v@n.leeuwen.net</a>&gt;:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">On Mon, Feb 12, 2007 at 03:08:27PM -0300, Ezequias Rodrigues da Rocha wrote:
<br>&gt; I mean really deadlock. Other transactions can&#39;t access the database until<br>&gt; the main transaction is complete.<br><br>What you describe sounds like a blocking lock: one transaction uses a<br>resource and another has to wait until it is not locked anymore
<br><br>A deadlock is a special case: two transactions both need resources A and<br>B. transaction 1 locks A, and the next moment transaction 2 locks B. Now<br>transaction 1 waits for 2 to release B, but at the same time 2 waits for 1
<br>to release A. This is called a deadlock, or circulair lock.<br>Postgresql automatically detects such a situation and rolls one of them<br>back. The client recieves a &#39;restartable database error&#39; and that is<br>
exactly true: ususally another try will work.<br><br>One method of fixing deadlocks is to make sure all your code accesses the<br>database in the same order. Alphabetically is easiest to remember...<br></blockquote></div>

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