From: Daniel Waite <rabbitblue@...>
Date: 2007-11-03T04:14:23+09:00
Subject: Re: Database speed issues

Jeremy Woertink wrote:
> So, I have a bit of a design problem. I have an application that work,
> but not as well as I would like it to. My problem is that I had to
> write an application that checks millions of records against hundreds
> of millions of records to see if there are any duplicates. The only
> way I could think to do this is pretty much select from the different
> tables where the specific column matches my search string. This is
> really slow! Obviously if it returns something, then  there is a dup,
> if not, then YAY!
> 
> I know there has to be a better way then just doing a SQL select
> statement. Any ideas?

I dunno how fast it is compared to your select statement, but if you can 
build  arrays out of the data you want to compare you call the % method 
on them. Example...

irb>  [ 5, 10 ] & [ 10, 15 ]
=> [10]

It works with more complex arrays, too...

irb>  [ [ 5, 10 ], [ 15, 20 ] ] & [ [ 10, 15 ], [ 5, 10] ]
=> [[5, 10]]

Hope that helps...
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