uwe at kiewel-online
Apr 14, 2008, 12:33 PM
Post #5 of 5
(259 views)
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Paul J Stevens schrieb:
> Uwe Kiewel wrote:
>> Hi Paul,
>>
>> Paul J Stevens schrieb:
>>> Uwe,
>>> please run that query through an 'ANALYZE' command.
>
> I meant 'DESCRIBE ...'
>
>
>
looks normal:
mysql> describe SELECT 'a',COUNT(*) FROM dbmail_messages WHERE
mailbox_idnr=121 AND (status < 2) UNION SELECT 'b',COUNT(*) FROM
dbmail_messages WHERE mailbox_idnr=121 AND (status < 2) AND seen_flag=1
UNION SELECT 'c',COUNT(*) FROM dbmail_messages WHERE mailbox_idnr=121
AND (status < 2) AND recent_flag=1;
+----+--------------+-----------------+------+----------------------------------------------------------------+--------------------+---------+-------+------+-------------+
| id | select_type | table | type | possible_keys
| key | key_len |
ref | rows | Extra |
+----+--------------+-----------------+------+----------------------------------------------------------------+--------------------+---------+-------+------+-------------+
| 1 | PRIMARY | dbmail_messages | ref |
mailbox_idnr_index,status_index,mailbox_status |
mailbox_idnr_index | 8 | const | 2 | Using where |
| 2 | UNION | dbmail_messages | ref |
mailbox_idnr_index,seen_flag_index,status_index,mailbox_status |
mailbox_idnr_index | 8 | const | 2 | Using where |
| 3 | UNION | dbmail_messages | ref |
mailbox_idnr_index,status_index,mailbox_status |
mailbox_idnr_index | 8 | const | 2 | Using where |
| NULL | UNION RESULT | <union1,2,3> | ALL | NULL
| NULL | NULL |
NULL | NULL | |
+----+--------------+-----------------+------+----------------------------------------------------------------+--------------------+---------+-------+------+-------------+
4 rows in set (0.02 sec)
another format of the output might be better readable:
mysql> explain SELECT 'a',COUNT(*) FROM dbmail_messages WHERE
mailbox_idnr=121 AND (status < 2) UNION SELECT 'b',COUNT(*) FROM
dbmail_messages WHERE mailbox_idnr=121 AND (status < 2) AND seen_flag=1
UNION SELECT 'c',COUNT(*) FROM dbmail_messages WHERE mailbox_idnr=121
AND (status < 2) AND recent_flag=1\G
*************************** 1. row ***************************
id: 1
select_type: PRIMARY
table: dbmail_messages
type: ref
possible_keys: mailbox_idnr_index,status_index,mailbox_status
key: mailbox_idnr_index
key_len: 8
ref: const
rows: 2
Extra: Using where
*************************** 2. row ***************************
id: 2
select_type: UNION
table: dbmail_messages
type: ref
possible_keys:
mailbox_idnr_index,seen_flag_index,status_index,mailbox_status
key: mailbox_idnr_index
key_len: 8
ref: const
rows: 2
Extra: Using where
*************************** 3. row ***************************
id: 3
select_type: UNION
table: dbmail_messages
type: ref
possible_keys: mailbox_idnr_index,status_index,mailbox_status
key: mailbox_idnr_index
key_len: 8
ref: const
rows: 2
Extra: Using where
*************************** 4. row ***************************
id: NULL
select_type: UNION RESULT
table: <union1,2,3>
type: ALL
possible_keys: NULL
key: NULL
key_len: NULL
ref: NULL
rows: NULL
Extra:
4 rows in set (0.00 sec)
Thanks,
Uwe
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