On Jan 8, 2008, at 8:24 AM, Jamie Tufnell wrote:
Hi,
I have a table that stores per-user histories of recently viewed items
and I'd like to limit the amount of history items to <= 50 per user.
I'm considering doing this with a query run from cron every so often
but I'm not happy with what I've come up with so far, and since it's a
quite active table I thought I'd ask here to see if there's a more
efficient way.
Right now the table structure is as follows...
user_item_history: id (PK), user_id (FK), item_id (FK), timestamp
For user_ids that have more than 50 rows, I want to keep the most
recent 50 and delete the rest.
Create an row trigger that fires after insert containing something
along the lines of :
DELETE FROM user_item_history
WHERE id IN (SELECT id
FROM user_item_history
WHERE user_id=NEW.user_id
ORDER BY timestamp DESC
OFFSET 50);
Erik Jones
DBA | Emma®
[EMAIL PROTECTED]
800.595.4401 or 615.292.5888
615.292.0777 (fax)
Emma helps organizations everywhere communicate & market in style.
Visit us online at http://www.myemma.com
---------------------------(end of broadcast)---------------------------
TIP 2: Don't 'kill -9' the postmaster
