Brion Vibber wrote:
Jitse Niesen wrote:
Why is DB_MASTER used instead of DB_SLAVE?
Lagged slaves were too unreliable; you would often see the previous version
after saving an edit.
Note that it in a typical page view, it only loads the page table row from
the master. It then tries to load the revision and text rows from a slave
using the up-to-date revision ID given by the master. If the revision is not
present, it falls back to a load from the master. The overhead from doing
this short, simple page table query to the master appears to be minimal.
Most of the other operations in Article.php are write operations, and thus
need the master connection.
-- Tim Starling