maybe you heva to declare a compound index with userid and username.
the sql parser now does not use the index on username.
----- Original Message -----
From: "David Wolf" <[EMAIL PROTECTED]>
To: "Tore Van Grembergen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Sunday, October 28, 2001 4:46 PM
Subject: Re: Optimizing query (2nd attempt)
> Yes.. There is an index on users.username :)
>
> David
>
> ----- Original Message -----
> From: "Tore Van Grembergen" <[EMAIL PROTECTED]>
> To: "David Wolf" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> Sent: Sunday, October 28, 2001 8:46 AM
> Subject: Re: Optimizing query (2nd attempt)
>
>
> > do you have an index defined on users.username ?
> >
> >
> > ----- Original Message -----
> > From: "David Wolf" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Sunday, October 28, 2001 4:26 PM
> > Subject: Optimizing query (2nd attempt)
> >
> >
> > > I have a query as follows:
> > >
> > > SELECT log.entity, log.action,
> > > LEFT(users.username,10) AS username,
> > > LEFT(boards.title,15) AS Board,
> > > LEFT(topics.subject,22) as Subject,
> > > log.postid, log.extraid,
> > > LEFT(from_unixtime(log.logtime),19) AS time, log.ip
> > > FROM log LEFT JOIN users ON log.userid = users.id
> > > LEFT JOIN boards ON log.boardid=boards.id
> > > LEFT JOIN topics ON log.topicid = topics.id
> > > WHERE log.logTime > UNIX_TIMESTAMP("2000-10-26 23:00:00")
> > > AND users.username="testuser";
> > >
> > > When I run an 'explain' on it, I get:
> > >
> > >
> >
>
+--------+--------+---------------+---------+---------+-------------+-------
> > > --+------------+
> > > | table | type | possible_keys | key | key_len | ref |
> rows
> > > | Extra |
> > >
> >
>
+--------+--------+---------------+---------+---------+-------------+-------
> > > --+------------+
> > > | log | ALL | time | NULL | NULL | NULL |
> > > 1192384 | where used |
> > > | users | eq_ref | PRIMARY | PRIMARY | 4 | log.userId |
> > > 1 | where used |
> > > | boards | eq_ref | PRIMARY | PRIMARY | 4 | log.boardId |
> > > 1 | |
> > > | topics | eq_ref | PRIMARY | PRIMARY | 4 | log.topicId |
> > > 1 | |
> > >
> >
>
+--------+--------+---------------+---------+---------+-------------+-------
> > > --+------------+
> > > 4 rows in set (0.01 sec)
> > >
> > > Now.. If I exclude the 'users.username="testuser"' and substitute it
for
> > the
> > > userid that I got in a previous query (i.e. userid=2) so that the
query
> > > becomes:
> > >
> > > SELECT log.entity, log.action,
> > > LEFT(users.username,10) AS username,
> > > LEFT(boards.title,15) AS Board,
> > > LEFT(topics.subject,22) as Subject,
> > > log.postid, log.extraid,
> > > LEFT(from_unixtime(log.logtime),19) AS time, log.ip
> > > FROM log LEFT JOIN users ON log.userid = users.id
> > > LEFT JOIN boards ON log.boardid=boards.id
> > > LEFT JOIN topics ON log.topicid = topics.id
> > > WHERE log.logTime > UNIX_TIMESTAMP("2000-10-26 23:00:00")
> > > AND log.userid=2;
> > >
> > >
> > > and run an explain, I get...
> > >
> > >
> >
>
+--------+--------+---------------+---------+---------+-------------+-------
> > > +------------+
> > > | table | type | possible_keys | key | key_len | ref |
> rows
> > > | Extra |
> > >
> >
>
+--------+--------+---------------+---------+---------+-------------+-------
> > > +------------+
> > > | log | ref | time,userid | userid | 4 | const |
> > 27198
> > > | where used |
> > > | users | eq_ref | PRIMARY | PRIMARY | 4 | log.userId |
> > 1
> > > | |
> > > | boards | eq_ref | PRIMARY | PRIMARY | 4 | log.boardId |
> > 1
> > > | |
> > > | topics | eq_ref | PRIMARY | PRIMARY | 4 | log.topicId |
> > 1
> > > | |
> > >
> >
>
+--------+--------+---------------+---------+---------+-------------+-------
> > > +------------+
> > > 4 rows in set (0.00 sec)
> > >
> > > Big difference from 1.19million rows to 27198 rows... My question is
> this.
> > > How can I optimize the query with the left joins so that the optimizer
> > will
> > > first grab the userid from the username and then use the userid index
on
> > log
> > > to return the results fast?
> > >
> > > Thanks in advance,
> > >
> > > David
> > >
> > >
> > >
> > >
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