From: Marnen Laibow-Koser <marnen@...>
Date: 2009-11-26T05:42:31+09:00
Subject: Re: Pseudo array for Rails migration

Ralph Shnelvar wrote:
> Wednesday, November 25, 2009, 10:35:06 AM, you wrote:
> 
> RK> On 22.11.2009 17:05, Marnen Laibow-Koser wrote:
>>>>
>>>> normalizing it slows me down a couple of orders of magnitude.  I'm
>>>> willing to live with the lack of purity for the sake of performance.
>>> 
>>> A couple orders of magnitude?   This suggests to me that your 
>>> normalization and/or queries are poorly done.  What is chewing up so 
>>> much time, and what does the normalized schema look like?  It should be 
>>> possible to find a solution that performs reasonably and doesn't have 20 
>>> repeating fields.
> 
> RK> I second that.  Ralph, any information about the slowness?  Is it in 
> the
> RK> database or outside?
> 
> I _think_ it is, in part, coming from the logging that is being done.
> 
> Instead of one create ... one can have 21.

Then, as I suspected, you are using the DB incorrectly.  To create 21 
records, use 1 query, not 21.  You can use ar-extensions or something 
similar to do this with ActiveRecord.

Rule of thumb: queries don't belong inside loops.  If you find yourself 
putting a query in a loop, you have a design problem.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
-- 
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