>>>>> "CP" == Collin Peters <cpeters@mcrt.ca> writes:
CP> I have thought of the following situations:
CP> -Simply track all the changes you made to the development database and
CP> make the same changes to the release database
CP> -Back up the release database... overwrite it with the development
CP> database... then copy all your real data back into the release
CP> database (this last step is probably quite difficult)
CP> -Perhaps some combination of the two
You need one more layer: the staging server.
What we do is develop on local workstations, prepare release on a
staging server, then push the staging server info to the production
box, or run the same updating script on production.
Any schema changes are done via scripts within transactions. The
renames, alters, grants, etc., are all tested on the staging server
with a current copy (pg_dump/restore) from the live server so we know
there won't be any surprizes on the live data (or close to it). It
also lets us know how long some things might take.
For example, this weekend we need to add a primary key to a 65 million
row table that just logs events. Until now it really didn't need a PK
since it was never updated and the queries were all aggregates.
However, to run slony replication it needs a PK... The test procedure
of doing it on the staging server pointed out some flaws in the
conversion script that were not noticed when running on the
development server because the dataset was so small. These flaws
would have made the DB unusable for something like 5 days (if it ever
completed -- I don't know because I aborted that test) while the
update occurred, and once done would leave the application without
access to the revised table. Naturally, we found better ways to do it
that have trimmed the expected time down to about 1.5 hours or less.
You really have to take each situation separately. The easy way of
the PK adding script works fine on tables up to about 60k or 100k
rows, so we used that on some other smaller tables.
--
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Vivek Khera, Ph.D. Khera Communications, Inc.
Internet: khera@kciLink.com Rockville, MD +1-301-869-4449 x806
AIM: vivekkhera Y!: vivek_khera http://www.khera.org/~vivek/