The fact that the explain didn't say "Index used".
--Russell
----- Original Message -----
From: "Philip Brown" <phil@stripped>
To: "Russell Miller" <duskglow2000@stripped>; <mysql@stripped>
Sent: Friday, October 05, 2001 4:00 PM
Subject: RE: Bizarre query performance
> > It doesn't look like you are using an index. Have you tried creating
one
> > and seeing what the effect on execution time is?
>
> What makes you think the index isn't being used?
> EXPLAIN SELECT * FROM X WHERE (PRIMARY KEY) = N looks like it is using
> the primary key. However, just to check I created a specific unique index
> on that value but performance was the same.
>
> The second query is using the index on ScheduledStart, which is correct
> and fine. That query works fine. It looks like the queries on the primary
> key are the one's that have odd behaviour.
>
> >
> > --Russell
> >
> > ----- Original Message -----
> > From: "Philip Brown" <phil@stripped>
> > To: "Russell Miller" <duskglow2000@stripped>;
> <mysql@stripped>
> > Sent: Friday, October 05, 2001 1:34 PM
> > Subject: RE: Bizarre query performance
> >
> >
> > > > Have you tried "explain"ing the two select to see where all
> > the time is
> > > > being spent and how the queries are optimized?
> > >
> > > Sorry, I should have included that in my detail.
> > >
> > >
> > +-------+-------+---------------+---------+---------+-------+-----
> > -+-------+
> > > | table | type | possible_keys | key | key_len | ref |
> > rows | Extra
> > |
> > >
> > +-------+-------+---------------+---------+---------+-------+-----
> > -+-------+
> > > | X | const | PRIMARY,p1 | PRIMARY | 4 | const | 1 |
> > |
> > >
> > +-------+-------+---------------+---------+---------+-------+-----
> > -+-------+
> > >
> > > This is the query that takes 200ms. It performs the same
> > regardless of the
> > > particular table involved (all have a similar primary key), or
> > the record
> > > fetched.
> > >
> > >
> > +------+-------+----------------+----------------+---------+------
> > +------+--
> > > ----------+
> > > | table| type | possible_keys | key | key_len |
> > ref | rows |
> > > Extra |
> > >
> > +------+-------+----------------+----------------+---------+------
> > +------+--
> > > ----------+
> > > | X | range | ScheduledStart | ScheduledStart | 8 |
> > NULL | 25 |
> > > where used |
> > >
> > +------+-------+----------------+----------------+---------+------
> > +------+--
> > > ----------+
> > >
> > > This is the query that takes less than 10ms. Performance should be
worse
> > > than that
> > > above, but it is not.
> >
> >
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> >
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