On 2/5/08, Tim Starling <tstarling(a)wikimedia.org> wrote:
Another way to find a previous revision is to order by
rev_id. But rev_id
is not monotonic with respect to time, due to various accidents of
history. There are step discontinuities, such as those introduced by
undeletion or the conversion script. It is however used by the older/newer
links on the old revision views. This algorithm is chosen over the
timestamp algorithm because at the time the revision is fetched, the
timestamp is not known, only the rev_id is known. Finding out the
timestamp would require an extra query.
I'm guessing a one-time re-assignment of rev_id's for edits older than
[timestamp of most recent discontinuity] is out of the question :-)
—C.W.