[wp-hackers] Extending query_posts?

[Scott johnson]

What I used to do back at my last gig was, for sequential data, get a min /
max and then use php's rand function and then use a select (since auto
increments are consecutive).  And then use a recursive function if the
autoincrement id didn't exist for example.

The problem here is that whenever we did it we found that users rarely if
ever wanted true randomness.  Its almost always some type of "random but
within a set" and "wait for the details" type of thing.

now bear in mind my last gig was "index the blogosphere" (Feedster) which is
worlds different.  A lot of times 2 random selections would get data from
the same feed since we indexed data in order it was received. (hence the
comment about users not really wanting random).

Scott

On 1/31/06, David Chait <davebytes at comcast.net> wrote:
>
> If you are trying to do anything like CG-SameCat, the approach I used was
> to
> not use random in the select, but select posts (well, post ID and title
> really...) where the category matches, ordered by post ID (or date)
> descending, and limit of some factor time the number of random items asked
> for... Thus, you want say three random, but recent, related posts -- so
> grab
> the last 10 or 20 and then use PHP to pick a random few from the
> set.  Just
> a thought.
>
> Completely random from entire posts table != completely random from recent
> posts in matching category... ;)
>
> -d
>
> ----- Original Message -----
> From: "Mattias Winther" <mattias at winthernet.se>
> To: <wp-hackers at lists.automattic.com>
> Sent: Tuesday, January 31, 2006 7:12 PM
> Subject: Re: [wp-hackers] Extending query_posts?
>
>
> |
> | Thanks, great link!
> |
> | Well, as for my own blog, I'm using to generate recent posts in the same
> category, meaning that I'll have quite the long way to go before 1000 hits
> is becoming an issue. Then again, I would like to do a nice plug-in that
> can
> be trusted to perform at about the same speed with a ton of rows.
> |
> | I guess it's time to brush up on my SQL.
> |
> | /Mattias
> |
> | On Tue, 31 Jan 2006 13:36:45 -0500, "David Chait" <davebytes at comcast.net
> >
> wrote:
> | > 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
> | >
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> |
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