Stephen R. van den Berg wrote:
>Tom Lane wrote:
>>Then use ctid.
>Hmmm, I didn't know about ctid. It does seem to allow me to distinguish
>values. It will require a SELECT followed by a DELETE or UPDATE though
>AFAICS. But I agree that it seems to solve my problem.
Funny, actually.
I just changed my application from doing a:
DELETE FROM a WHERE b=3 LIMIT 1;
to:
DELETE FROM a WHERE ctid=(SELECT ctid FROM a WHERE b=3 LIMIT 1);
It works.
Actually, it works *identically*, i.e. the actual row deleted is
just as randomly chosen as in the DELETE with LIMIT case.
The first version looks cleaner to me (and better understandable) though.
Incidentally, using a SELECT without an ORDER BY but with a LIMIT is
documented to give unpredictable results, yet users are expected cope with
this fact, but are expected to have problems with a similar fact in
an UPDATE or DELETE statement?
Somehow the argumentation is not conclusive.
--
Sincerely, srb@cuci.nl
Stephen R. van den Berg (AKA BuGless).
Do more than anyone expects, and pretty soon everyone will expect more.
