You have a function on a field in the where clause, so no index can be used.
Do your date_add() on the NOW() and compare it directly to the field.
Ireneusz Piasecki wrote:
>Hi folks.
>I have table:
>
>mysql> describe gosc;
>+-------------+---------------------+------+-----+---------------------+----
>---+
>| Field | Type | Null | Key | Default |
>Extra |
>+-------------+---------------------+------+-----+---------------------+----
>---+
>| sesja | varchar(32) binary | | PRI | |
>|
>| host | varchar(80) | YES | MUL | NULL |
>|
>| data_wej | datetime | | MUL | 0000-00-00 00:00:00 |
>|
>| browser | varchar(100) | YES | | NULL |
>|
>| last_action | datetime | | MUL | 0000-00-00 00:00:00 |
>|
>| id_pory1 | int(3) unsigned | YES | | NULL |
>|
>| id_pory2 | int(3) unsigned | YES | | NULL |
>|
>| nr_ip | varchar(15) | YES | | NULL |
>|
>| id_user | bigint(12) unsigned | | MUL | 0 |
>|
>| user_log | varchar(150) | | | 0- |
>|
>+-------------+---------------------+------+-----+---------------------+----
>---+
>10 rows in set (1.39 sec)
>
>
>I made:
>
>mysql> explain select sesja,data_wej,id_user,user_log,nr_ip from gosc where
>date_add(last_action, interval 5 minute) > now();
>+-------+------+---------------+------+---------+------+-------+------------
>+
>| table | type | possible_keys | key | key_len | ref | rows | Extra
>|
>+-------+------+---------------+------+---------+------+-------+------------
>+
>| gosc | ALL | NULL | NULL | NULL | NULL | 37803 | where used
>|
>+-------+------+---------------+------+---------+------+-------+------------
>+
>
>Is my table good indexed ?? Or maybe this query above can be faster ??
>
>Regards
>
>Ireneusz Piasecki
>
>
>
