From: Brian Le Roy <brian@...>
Date: 2005-09-09T23:55:46+09:00
Subject: Re: general performance question

Thanks Robert!

I think I found the culprit.

With 20 records in the result:
total ms/call
12300.00  Mysql::Result#each

With 1 record in the result:
total ms/call
600.00  Mysql::Result#each

The query behind this result set is indexed properly.  Not sure why this 
takes so long - shouldn't it be as fast as a regular array.each call?

Robert Klemme wrote:
> Brian Le Roy wrote:
> 
>>Actually guys, I took out the queries - except for one that is run
>>  once. Same behaviour in top.  I'm going to start marking out the
>>app with
>>the benchmark module and hopefully that will shed some light on it!
> 
> 
> Note also that there is ruby -r profile.  That way you don't have to
> manually change your code.
> 
>     robert
> 
> 
>>Robert Klemme wrote:
>>
>>>Reid Thompson <reid.thompson@ateb.com> wrote:
>>>
>>>
>>>>Brian Le Roy wrote:
>>>>
>>>>
>>>>>no, but the table has 140K records.  the disk isn't crunching, so
>>>>>the index should be okay.  i was thinking it would be passing
>>>>>around the database connection object causing overhead.  i took
>>>>>the result set object and created a straight ol' array for
>>>>>passing.  no improvement - so maybe there's nothing to do.  thanks
>>>>>for all the responses - i'll keep messing with it and if i find
>>>>>something that improves it, i'll let you know!
>>>>>
>>>>>bonefry wrote:
>>>>>
>>>>>
>>>>>>Well, that's it.
>>>>>>
>>>>>>MySql can take even 100% of your processing power. It happenes
>>>>>>when you have complex queries to run, and you run them on big
>>>>>>tables. Are you running complex queries ?
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>It may may no difference, but you could try the same with
>>>>postgresql, or maybe even sqlite, to see if it is mysql thats the
>>>>issue.
>>>
>>>
>>>Before he does that I'd try a different query frontend to see whether
>>>performance characteristics stay the same (i.e. time is spent in the
>>>DB, which would be my guess).  The overhead is much smaller compared
>>>to installing another DBMS, transferring DDL and data to that.
>>>
>>>Kind regards
>>>
>>>   robert
> 
> 
> 
>