hi list,
i have a very strange effect.

I have two boxes with the same DB ( same version, same tables, same my.cnf, etc)
I was trying to optimise an sql statement and used desc to see what is going on
and found to my surprise two different results.

Can this be the result of the optimizer ? (the boxes have very different uptime)
re,
wh

here the output of "desc statement;"

+----+--------------------+-------+--------+---------------- ---+---------+---------+----------------+------+------------ --------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+-------+--------+---------------- ---+---------+---------+----------------+------+------------ --------------+
| 1 | PRIMARY | D | ref | PRIMARY,fk_mk_d | fk_mk_d | 2 | const | 1087 | Using where |
| 1 | PRIMARY | A | ref | PRIMARY,fk_mms_sb | PRIMARY | 4 | D.kenn | 198 | Using where |
| 1 | PRIMARY | B | eq_ref | PRIMARY | PRIMARY | 3 | A.code | 1 | |
| 2 | DEPENDENT SUBQUERY | C | ref | PRIMARY,fk_mms_sb | PRIMARY | 4 | D.kenn | 165 | Using where; Using index |
+----+--------------------+-------+--------+---------------- ---+---------+---------+----------------+------+------------ --------------+


+----+--------------------+-------+--------+---------------- ---+-----------+---------+----------------+------+---------- ----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+--------------------+-------+--------+---------------- ---+-----------+---------+----------------+------+---------- ----------------+
| 1 | PRIMARY | B | ALL | PRIMARY | NULL | NULL | NULL | 29 | Using where |
| 1 | PRIMARY | A | ref | PRIMARY,fk_mms_sb | fk_mms_sb | 3 | B.code | 2035 | Using where |
| 1 | PRIMARY | D | eq_ref | PRIMARY,fk_mk_d | PRIMARY | 4 | A.kenn | 1 | Using where |
| 2 | DEPENDENT SUBQUERY | C | ref | PRIMARY,fk_mms_sb | PRIMARY | 4 | D.kenn | 574 | Using where; Using index |
+----+--------------------+-------+--------+---------------- ---+-----------+---------+----------------+------+---------- ----------------+

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Exactly the same data, too? Different index leaf distribution might account for something like this, and it does look like you're retrieving different datasets.

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Am 31.08.2011 13:51, schrieb Johan De Meersman:
> Exactly the same data, too? Different index leaf distribution might account for something
>like this, and it does look like you're retrieving different datasets.
>

same data

think of it as a backup.

re,
wh

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