The list looks a lot like the top of Saints in our Book,

That was my first thought until I noticed the absence of Abigail-II.

Now he hasn't been around for a couple of years, which (I think) is longer than anyone else on the list. That suggests that the time threshold in the query that fetches the list of users that have been active in the last few minutes, has been screwed up.

Perhaps a limit that should have been set in minutes has been set in seconds? Or similar.

Great diagnosis!

In fact, it was this small change that broke all node sets that were user lists and should reflect the "recent" users:

Originally, there was this query, which did not use an index on lasttime:

                SELECT node_id    pick_id,
                       title      pickname,
                       node_id    auth_id,
                       title      authname,
                       experience rep
                  FROM node,
                       user
                 WHERE node_id = user_id
                  AND (UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(lasttime
+) < ?)
              ORDER BY experience $args{order},
                       node_id ASC
                LIMIT  $limit
[download]

I eliminated the function on lasttime by converting the date math from math on integers/unix timestamps to math on datetime types:

                SELECT node_id    pick_id,
                       title      pickname,
                       node_id    auth_id,
                       title      authname,
                       experience rep
                  FROM node,
                       user
                 WHERE node_id = user_id
                   AND lasttime > date_sub(NOW(), INTERVAL ? DAY)
              ORDER BY experience $args{order},
                       node_id ASC
                LIMIT  $limit
[download]

which now used days where it should have used seconds:

                SELECT node_id    pick_id,
                       title      pickname,
                       node_id    auth_id,
                       title      authname,
                       experience rep
                  FROM node,
                       user
                 WHERE node_id = user_id
                   AND lasttime > date_sub(NOW(), INTERVAL ? SECOND)
              ORDER BY experience $args{order},
                       node_id ASC
                LIMIT  $limit
[download]

As my excuse, there was a similar-yet-different code path further above, where the same parameters were used for non-user nodes that were in days, instead of seconds :-)).

Wow, good you were not programming the Doomsday Machine!

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James