Re: Speeding up Aggregates

Dror,

> select articlenumber, channel, description, title, link, dtstamp from
> items, my_channels where items.channel = '22222' and my_channels.id =
> '22222' and owner = 'drormata' and dtstamp > last_viewed and
> articlenumber not in (select item from viewed_items where channel
> ='22222' and owner = 'drormata');

the NOT IN is a bad idea unless the subselect never returns more than a
handful of rows. If viewed_items can grow to dozens of rows, wyou should
use WHERE NOT EXISTS instead. Unless you're using 7.4.

> item_max_date() looks like this:
> select max(dtstamp) from items where channel = $1 and link = $2;

Change it to

SELECT dtstamp from iterm where channel = $1 and link = $2
ORDER BY dtstamp DESC LIMIT 1

and possibly build an index on channel, link, dtstamp

--
-Josh Berkus
Aglio Database Solutions
San Francisco