From: Stefan Rusterholz <apeiros@...>
Date: 2007-05-24T07:15:25+09:00
Subject: Re: optimizing for speed - Array#each

Mike Steiner wrote:
> I ran the profiler on my program and it said that 51% of the time is 
> spent
> in Array#each. Is there any way to speed this up (like using
> Array#each_index perhaps)?
> 
> And is there a quicker way to do a .gsub if I'm using just strings and 
> not a
> regexp?
> 
> By the way, the program compares 2 databases and determines which 
> records
> have been inserted and deleted, and each database has about 15,000 
> records
> to compare.
> 
> Mike Steiner

No. I don't think you can speed up Array#each at all. What's far more 
promising is improving your algorithm in a way that it has to run less 
loops. You most likely have one or even several O(n^x) algorithms with x 
>= 2 in your app. Maybe you're not even aware. E.g. if you have an each 
with a select in the loop you're already in O(n^2) realm.
The database comparison probably can be handled best with hashtables of 
the primary keys.

Regards
Stefan

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