| From: | "Florian G(dot) Pflug" <fgp(at)phlo(dot)org> |
|---|---|
| To: | DANTE Alexandra <Alexandra(dot)Dante(at)bull(dot)net>, pgsql-general(at)postgresql(dot)org, kleptog(at)svana(dot)org |
| Subject: | Re: Questions about update, delete, ctid... |
| Date: | 2006-07-30 14:37:26 |
| Message-ID: | 44CCC426.4080408@phlo.org |
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| Lists: | pgsql-general |
Martijn van Oosterhout wrote:
> On Fri, Jul 28, 2006 at 12:00:19PM +0200, DANTE Alexandra wrote:
>> - is it correct to think that the ctid of the old version of the tuple
>> is a link to newer version ? In my example, is it correct to think that
>> the tuple :
>> 140049 | 0 | (0,12) | 11 | IRAQ
>> has become :
>> new value | 0 | (0,26) | 11 | ITALY
>
> The word "become" is not really right. The old version has become
> invisible to you and the new version is visible. Some other
> transactions will see the old one, some the new one. However, there is
> a link between the old and the new version do detect conflicting
> updates.
That sounds interesting... how is that link between old and new
tuple implemented? I've been playing with the idea to implement
"update table foo where current of <cursor>", and such a link
would help tremendously. I read the code, but couldn't find any
such link - which part of the code should I read closer?
greetings, Florian Pflug
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