Re: Referential Integrity and SHARE locks

From: "Simon Riggs" <simon(at)2ndquadrant(dot)com>
To: "Stephan Szabo" <sszabo(at)megazone(dot)bigpanda(dot)com>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Referential Integrity and SHARE locks
Date: 2007-02-02 20:19:44
Message-ID: 1170447585.3645.81.camel@silverbirch.site
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On Fri, 2007-02-02 at 10:35 -0800, Stephan Szabo wrote:
> On Fri, 2 Feb 2007, Simon Riggs wrote:
>
> > It sounds like if we don't put a SHARE lock on the referenced table then
> > we can end the transaction in an inconsistent state if the referenced
> > table has concurrent UPDATEs or DELETEs. BUT those operations do impose
> > locking rules back onto the referencing tables that would not be granted
> > until after any changes to the referencing table complete, whereupon
> > they would restrict or cascade. So an inconsistent state doesn't seem
> > possible to me.
>
> What locking back to the referencing table are you thinking about? The row
> locks are insufficient because that doesn't prevent an insert of a
> new row that matches the criteria previously locked against AFAIK.

Probably best to read the later posts; this one was at the beginning of
my thought train, so is slightly off track, as later posters remind me.

--
Simon Riggs
EnterpriseDB http://www.enterprisedb.com

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