Henning Schroeder wrote:
> At 17:52 06.09.01, you wrote:
>
> >It is copying ALL of the results into the temp table. If you can (e.g.
> >you know you will
> >never want more than N records), add a LIMIT 0,N to the end of the SELECT
> >so that when you
> >have an old timestamp it will not hang the database.
>
> as i use
>
> select count (*) from blah where blahblah;
>
> (actually i am just interested whether there is a row or not matching the
> criterion. under normal operations there should never be more than one match)
>
> i donīt understand how a limit 0,1 would help here. wouldnīt it just say
> that no more than one count(*) result should be returned (which never the
> case anyway because count(*) returns exactly one row)?
I misread your email. I thought you had a query that was 'copying into temp
table' that was not the COUNT(*) query. Rereading your email, I see that for
me it is better to remain silent than remove all doubt. ;-)
Do your two queries both take a long time? What if you add a key on type and
timestamp (in that order).
>select count(*) from adviews where click="f" and uid=7618 and cid=11 and
datestamp>=999782664;
>select count(*) from chat where type="msg" and timestamp>999783881;
--Bill
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