[wp-hackers] Extending query_posts?

[David Chait]

Yes, RAND is awful for ORDER BY.

http://jan.kneschke.de/projects/mysql/order-by-rand/

At the end, he shows times for 100, 1000, ... , 1M records.  RAND starts to 
'hurt' even when just 1000 records.  He walks through building an alternate 
approach, still in SQL (though using sub-selects, so MySQL 4.1+).

Do you need a completely random entry from the entire data set?  Or would a 
random-but-recent entry work? (i.e., select post_id limit 100, pick a random 
entry or entries, then do the 'full' query with post_id in {list of selected 
ids}...)

-d

----- Original Message ----- 
From: "Mattias Winther" <mattias at winthernet.se>
To: <wp-hackers at lists.automattic.com>
Sent: Tuesday, January 31, 2006 12:27 PM
Subject: Re: [wp-hackers] Extending query_posts?


|
| I can't find any specific references to the performance problems you are 
referring to... Anyone else out there who recognizes this, preferrably with 
some kind of link for further analysis? Or, someone with a huge database 
that can run the numbers?
|
| /Mattias
|
| On Mon, 30 Jan 2006 08:10:03 -0500, Scott johnson <fuzzygroup at gmail.com> 
wrote:
| > I'd be careful with that.  My understanding of randomization in mysql
| > is that the performance is awful.  I haven't done it myself but that's
| > hwat I understand.
| >
| > Scott