| From: | Richard Huxton <dev(at)archonet(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Sergey Konoplev <gray(dot)ru(at)gmail(dot)com>, pgsql-general(at)postgreSQL(dot)org |
| Subject: | Re: Very slow queries w/ NOT IN preparation (seems like a bug, test case) |
| Date: | 2008-11-11 13:27:03 |
| Message-ID: | 49198827.3050703@archonet.com |
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| Lists: | pgsql-general pgsql-hackers |
Tom Lane wrote:
> Richard Huxton <dev(at)archonet(dot)com> writes:
>> I've never heard of EXPLAIN ANALYSE being *faster* than the actual
>> query, it's usually slower due to all the timing calls. The only thing
>> it doesn't do is actually send the results over the connection to the
>> client. In your case, you're not actually selecting any columns, so that
>> can't be it.
>
> If I'm reading it right the query returns 5000 instances of "1". So
> there's definitely scope for the client side to pose a performance
> issue.
But 34s for 5000 single values? Surely you'd loads of queries slow, not
just this "not in" query.
--
Richard Huxton
Archonet Ltd
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