How to find random records in a subset?

From: Date: Thu, 02 Jun 2005 23:31:31 +0000
Subject: How to find random records in a subset?
Groups: php.general 
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I am using a routine to find 50 random records in a large MySQL database (about a million records) where I generate a list of 50 random unique ID's, and then use MySQL's "in" command to find them. I can't use "order by rand()" due to its performance hit. But I have to take it one more step: I want to first limit my found set to those matching a different search criteria, and then find 50 of those. Anyone? Can this be done all within MySQL, or is it going to require some humongo PHP arrays?

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