BuddyPress uses ‘last_activity’ data extensively: for display purposes (‘last active 3 days ago’), to sort results, and to determine whether a WP user is a valid site member. At the same time, ‘last_activity’ has been a perennial performance bottleneck. In the case of users, the information was stored in
wp_usermeta. This table gets exceptionally bloated on busy sites, and it’s not properly indexed for the sorts of
ORDER BY queries we were performing on it. See #5128 for more background.
A fix for this longtime issue is in place for BuddyPress 2.0. (See r7860.) Short version: user last_activity data is now stored in a ‘last_activity’ row in the
wp_bp_activity table. We’ve modified our core queries to take advantage of the new location. And we’ve done a bit of trickery to make sure that the
wp_bp_activity table is available for storage, even if the Activity component is disabled. The performance improvements are pretty extreme; I’ll post benchmarks as we near 2.0’s release.
Plugin developers who use user ‘last_activity’ data are urged to account for the new schema. In the past, you may have accessed user last_activity like this:
update_user_meta( $user_id, 'last_activity', $time );
$last_activity = get_user_meta( $user_id, 'last_activity', true );
You are urged to use our API functions instead:
bp_update_user_last_activity( $user_id, $time );
$last_activity = bp_get_user_last_activity( $user_id );
In cases where you are making direct database queries based on this info, please consider using
BP_User_Query instead. At the very least, you should refactor your queries to use the new schema.
For the time being, ‘last_activity’ data will continue to be mirrored in
wp_usermeta, so your plugins will continue to work. However, you’ll get deprecated notices every time you use the
_user_meta() functions to access the information. And hey, the new way performs much better, so you’ll want to update anyway.
Here’s a list of the plugins I found in the wordpress.org plugin repo that will need updating:
Questions regarding this change? Need help migrating your code? Please leave a comment below.
(A quick note regarding ‘last_activity’ for groups and blogs. The basic problem there is the same as for users, but the scaling issues are much less severe, so they have not been touched for now. Keep an eye out for relevant updates.)