| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
| Cc: | DANTE Alexandra <Alexandra(dot)Dante(at)bull(dot)net>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Questions about update, delete, ctid... |
| Date: | 2006-07-31 12:25:17 |
| Message-ID: | 13104.1154348717@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> On Mon, Jul 31, 2006 at 11:04:58AM +0200, DANTE Alexandra wrote:
>> I've just seen that I've done a mistake in my example. My question was :
>> is it correct to think that the ctid of the old version of the tuple is
>> a link to newer version ?
> Well, in your case where there are no other transactions running, yes.
> In the general case there may have been other updates so all you know
> is that the new tuple is a descendant of the old one. The chain of
> t_ctid links can be arbitrarily long.
It's probably worth pointing out here that the "ctid" column exposed
at the SQL level is not the same as t_ctid --- it's what the C code calls
t_self.
regards, tom lane
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