At about 11pm (UK time) on August 9th the TRM database
was “pruned”, removing all TRMs apart from the ones attached to
MusicBrainz tracks. This resulted in the database becoming about
one-third of the size it was before.
Because the TRM database is smaller, it now fits into the server’s
memory, reducing the need for disk activity (which means the rest of
MusicBrainz runs faster too).
Because TRM requests can now be served from memory instead of from disk,
TRM responses are now much quicker,
which in turn means that
we don’t have to refuse as many TRM requests
due to the server being too busy.
(Note that most of those linked graphs started in mid March 2004,
just before the TRM server’s memory was upgraded. This explains why
several of the graphs start with a sudden change in behaviour.)
MetaBrainz Blog 