> 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" <[EMAIL PROTECTED]> > To: "Russell Miller" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> > 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. > > > _________________________________________________________ > Do You Yahoo!? > Get your free @yahoo.com address at http://mail.yahoo.com > > --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
