I fixed it.
Per Camponez's suggestion, I ran update.php on a test version of the
site and that fixed the
bloat there. So I ran update.php on production Teflpedia site also. It
cleared the objectcache table, which had grown to 743 MB, back to zero
which brings the database back down to expected size. The database is
now 148 MB instead of 933 MB. I think I will routinely run update.php
before backing up the database from now on and that should take care
of it.
I suspect this bit in LocalSettings.php, which sets $wgMainCacheType
to CACHE_DB, may have started this cache bloat building back in
February 2012:
## Shared memory settings
# Roger 21 Feb 2012 comments out original line below to try another value
# so that 3rd badlogin will trigger ConfirmEdit captcha
#$wgMainCacheType = CACHE_NONE;
$wgMainCacheType = CACHE_DB; // yea! badlogin trigger works with this
$wgMemCachedServers = array();
It appears that using the database as a chache works fine, as long as
I clear the cache from time to time. Running update.php once a month
as part of my backup routine will do the job I think. Unless someone
points me at a better way.
Thank you everyone for your replies and tips!
Once again, Mediawiki-l shines.
Roger :-)