| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Erick Papadakis <erick_papadakis(at)yahoo(dot)com> |
| Cc: | Martijn van Oosterhout <kleptog(at)svana(dot)org>, Nils Zonneveld <nils(at)mbit(dot)nl>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Re: Does PostgreSQL support EXISTS? |
| Date: | 2001-06-13 14:03:58 |
| Message-ID: | 200106131403.f5DE3wE03678@candle.pha.pa.us |
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| Lists: | pgsql-general |
> | On postgres at least, exists is faster than in.
> |
> | They are equivalent though.
> |
> | select x from a where v in (select v from b)
> | select x from a where exists (select 1 from b where a.v = b.v)
> | select x from a, b where a.v = b.v
> |
> | are all the same. Postgres doesn't quite know that yet though.
>
>
> If you do an EXPLAIN on Oracle with the first 2 queries above, you will
> notice that the second one is faster in Oracle too (i.e., EXISTS is faster
> than IN).
So it is confirmed. Interesting.
--
Bruce Momjian | http://candle.pha.pa.us
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