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From:Michael Widenius Date:July 29 1999 11:09pm
Subject:Calculating Query time
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>>>>> "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
Thread
Calculating Query time(Brandon Shuey)13 Jul
  • Re: Calculating Query timeChristian Mack17 Jul
  • Calculating Query timeMichael Widenius30 Jul
    • Re: Calculating Query timeBob Bowker30 Jul
      • Re: Calculating Query timeMartin Ramsch30 Jul