pg.ddx.io  pgsql-sql@postgresql.org mailing list archive  

help / color / mirror / Atom feed
From: Richard Huxton <dev@archonet.com>
To: Csaba Nagy <nagy@ecircle-ag.com>
Cc: ON.KG <skyer@on.kg>
Cc: Postgres general mailing list <pgsql-general@postgresql.org>
Subject: Re: duplicate key violates unique constraint
Date: Mon, 13 Jun 2005 16:49:15 +0100
Message-ID: <42ADAAFB.30404@archonet.com> (raw)
In-Reply-To: <1118676122.2720.24.camel@coppola.muc.ecircle.de>
References: <42A95936.3060002@archonet.com>
	<20050610095655.0215752956@svr1.postgresql.org>
	<10813889593.20050613202239@on.kg>
	<42AD9B9D.6080902@archonet.com>
	<1118676122.2720.24.camel@coppola.muc.ecircle.de>

Csaba Nagy wrote:
> [snip]
> 
>>If you have more than one client, this can always happen. You have two 
>>choices:
>>  1. Use a lock to stop two clients interacting like this
> 
> 
> This won't work unless you make all the clients serialized, or you have
> all the ip's already inserted in the data base... you can't lock on an
> unknown key, otherwise the locking will also need to insert, and you're
> back to the same race condition ;-)

You can, however, have something more finely-grained than whole-table 
locking (assuming one IP updated/inserted at a time) by filling a dummy 
table with e.g. integers 0..255 and locking a row there based on (e.g.) 
the last octet of your target IP.

--
   Richard Huxton
   Archonet Ltd



view thread (17+ messages)  latest in thread

Message-ID: <42ADAAFB.30404@archonet.com>
Permalink:  ../42ADAAFB.30404@archonet.com/
Also on:    postgresql.org/message-id/42ADAAFB.30404@archonet.com

 · 

reply
Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: pgsql-sql@postgresql.org
  Cc: dev@archonet.com, nagy@ecircle-ag.com, skyer@on.kg, pgsql-general@postgresql.org
  Subject: Re: duplicate key violates unique constraint
  In-Reply-To: <42ADAAFB.30404@archonet.com>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox