| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
| Cc: | Csaba Nagy <nagy(at)ecircle-ag(dot)com>, Postgres general mailing list <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: allow LIMIT in UPDATE and DELETE |
| Date: | 2006-05-19 16:57:23 |
| Message-ID: | 2296.1148057843@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> Err, you don't need an index on ctid because the ctid represents that
> physical location of the tuple on disk. ctids are what indexes use to
> refer to tuples...
> # explain DELETE FROM t WHERE ctid=(SELECT ctid FROM t WHERE pronargs=1 LIMIT 1);
This doesn't currently work for more than one tuple, though: the natural
locution would be "WHERE ctid IN (SELECT returning more than one tid)"
but the planner/executor don't cope with doing that efficiently. Might
be worth trying to fix that.
regards, tom lane
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