>>>>> "Brandon" == Brandon Shuey <brandon@stripped> writes:
Brandon> I know there should be a way of estimating how long a query will take to run.
> Is there some general formulas I can use? Do I need
Brandon> to run some kind of benchmark for the server Mysql runs on before calculating?
> Is there a rule of thumb?
Brandon> Here is an example: Server=Ultra 10, Solaris 2.x, 128Mbtye RAM, IDE
> HardDrive
mysql> explain SELECT
-> Date_Format(Date_Time,'%Y-%m-%d') as "Dates",
-> SourceAccount,
-> Source,
-> Count(*) as "Sponsorship Clichthrus 5/3 thru 5/9"
-> FROM tblGeneralClickthrus p
-> WHERE (p.Date_Time >= '1999-07-01' AND p.Date_Time < '1999-07-12')
-> GROUP BY Dates,SourceAccount,Source
-> ;
Brandon>
> +-------+------+---------------+------+---------+------+--------+------------+
Brandon> | table | type | possible_keys | key | key_len | ref | rows | Extra
> |
Brandon>
> +-------+------+---------------+------+---------+------+--------+------------+
Brandon> | p | ALL | Date_Time | NULL | NULL | NULL | 119597 | where used
> |
Brandon>
> +-------+------+---------------+------+---------+------+--------+------------+
Brandon> 1 row in set (0.10 sec)
You can get a 'rough' time by doing a multiplication on all values in
the 'rows' column in the explain output.
In the above case MySQL will have to examine 119597 rows while
executing the query.
Regards,
Monty
