Interesting setup. You're using one more join than you need to. Your query should look
like this:
SELECT
DISTINCT(fvr.DocumentID)
FROM
FieldValueRelation fvr
INNER JOIN
FieldValueRelation fvr2
ON fvr.DocumentID = fvr2.DocumentID
AND fvr2.FieldValueID = '1569'
WHERE fvr1.FieldValueID = '1344'
Your query was so slow because you were first selecting ALL the records from
FieldValueRelation, then using a join to filter out the
records. You should be using a WHERE clause to filter out the first data set.
----- Original Message -----
From: "Andrew Wood" <andrew.d.wood@stripped>
To: <mysql@stripped>
Sent: Tuesday, July 11, 2006 9:50 PM
Subject: Self Join Performance
> Hello everyone!
>
> I've got a few questions regarding optimizing self-joins.
> So I've got these three tables:
>
> mysql> describe FieldName;
> +-------------+------------+------+-----+---------+----------------+
> | Field | Type | Null | Key | Default | Extra |
> +-------------+------------+------+-----+---------+----------------+
> | FieldNameID | bigint(20) | NO | PRI | NULL | auto_increment |
> | Name | char(255) | YES | | NULL | |
> +-------------+------------+------+-----+---------+----------------+
> 2 rows in set (0.02 sec)
>
> mysql> describe FieldValue;
> +--------------+------------+------+-----+---------+----------------+
> | Field | Type | Null | Key | Default | Extra |
> +--------------+------------+------+-----+---------+----------------+
> | FieldValueID | bigint(20) | NO | PRI | NULL | auto_increment |
> | FieldNameID | bigint(20) | NO | MUL | NULL | |
> | Value | char(255) | YES | MUL | NULL | |
> +--------------+------------+------+-----+---------+----------------+
> 3 rows in set (0.00 sec)
>
> mysql> describe FieldValueRelation;
> +--------------+-------------+------+-----+---------+-------+
> | Field | Type | Null | Key | Default | Extra |
> +--------------+-------------+------+-----+---------+-------+
> | FieldValueID | bigint(20) | NO | MUL | NULL | |
> | DocumentID | bigint(20) | NO | MUL | NULL | |
> | FieldSetID | tinyint(11) | YES | | NULL | |
> +--------------+-------------+------+-----+---------+-------+
> 3 rows in set (0.00 sec)
>
>
> I've ran a script to populate the database with a decent set of
> randomized data (~7 million DocumentIDs). The following query may
> clear things up a bit:
>
>
> mysql> select * from FieldName, FieldValue, FieldValueRelation where
> DocumentID = '7000000' and FieldValue.FieldValueID =
> FieldValueRelation.FieldValueID and FieldName.FieldNameID =
> FieldValue.FieldNameID;
>
> +-------------+-----------+--------------+-------------+----------+--------------+------------+------------+
> | FieldNameID | Name | FieldValueID | FieldNameID | Value |
> FieldValueID | DocumentID | FieldSetID |
>
> +-------------+-----------+--------------+-------------+----------+--------------+------------+------------+
> | 1 | Account | 6737063 | 1 | 88116010 |
> 6737063 | 7000000 | NULL |
> | 2 | FirstName | 1344 | 2 | Noelle |
> 1344 | 7000000 | 1 |
> | 3 | LastName | 1569 | 3 | Shea |
> 1569 | 7000000 | 1 |
>
> +-------------+-----------+--------------+-------------+----------+--------------+------------+------------+
> 3 rows in set (0.00 sec)
>
>
>
> So here's my question: I want to be able to find all of the rows in
> the FieldValueRelation table that have both a FirstName of 'Noelle'
> and a LastName of 'Shea'. I've tried a few things, all of which have
> less than stellar performance. I'm guesstimating that I'll have to do
> a self join on the FieldValueRelation table. Alas, it's pretty darn
> slow:
>
> SELECT
> DISTINCT(fvr.DocumentID)
> FROM
> FieldValueRelation fvr
> INNER JOIN
> FieldValueRelation fvr1
> ON fvr.DocumentID = fvr1.DocumentID
> AND fvr1.FieldValueID = '1344'
> INNER JOIN
> FieldValueRelation fvr2
> ON fvr.DocumentID = fvr2.DocumentID
> AND fvr2.FieldValueID = '1569'
>
> And when I execute it:
>
> +------------+
> | DocumentID |
> +------------+
> | 162955 |
> | 721704 |
> | 993290 |
> | 1606157 |
> | 2459823 |
> | 2759626 |
> | 3949779 |
> | 5192230 |
> | 5753563 |
> | 6616602 |
> | 7000000 |
> +------------+
> 11 rows in set (37.33 sec)
>
> 37 seconds is a bit long for what I'd like to use this schema for. So
> here's the counts for the matching FieldValueIDs (if this helps):
>
> mysql> select count(*) from FieldValueRelation where FieldValueID = '1569';
> +----------+
> | count(*) |
> +----------+
> | 7753 |
> +----------+
> 1 row in set (0.05 sec)
>
> mysql> select count(*) from FieldValueRelation where FieldValueID = '1344';
> +----------+
> | count(*) |
> +----------+
> | 7357 |
> +----------+
> 1 row in set (0.01 sec)
>
>
> Can anyone shed any light on this?
>
> --
> Cheers,
> -Andrew
>
>
> All generalizations, with the possible exception of this one, are false.
> - Kurt Goedel
>
> --
> MySQL General Mailing List
> For list archives: http://lists.mysql.com/mysql
> To unsubscribe: http://lists.mysql.com/mysql?unsub=1
>
