On Tue, Jun 23, 2009 at 1:12 PM, Mathieu Nebra<mateo21@xxxxxxxxxxxxxx> wrote: > The flags table keeps track of every topic a member has visited and > remembers the last answer which was posted at this moment. It allows the > user to come back a few days after and immediately jump to the last > answer he has not read. I forgot to mention that we speed up our queries by caching the "last read" ID in Memcached. This is the kind of thing that Memcached is ideal for. For example, we show the list of the most recent posts, along with a comment count, eg. "42 comments (6 new)". We found that joining posts against the last-read table is expensive, so instead we read from Memcached on every post to find the number of unread comments. We use the thread's "last commented at" timestamp as part of the key so that when somebody posts a new comment, every user's cached unread count is invalidated; it is automatically recalculated the next time they view the post. A. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
