> So, it appears my autovacuum is just NOT working... I must have screwed something up, but I cannot see what.
Is it possible that you have long running transactions ? If yes, VACUUM
is simply not efficient, as it won't eliminate the dead space
accumulated during the long running transaction. In that case VACUUM
FULL won't help you either as it also can't eliminate dead space still
visible by old transactions, but from what you say I guess you really
stop everything before doing VACUUM FULL so you might as well stopped
the culprit transaction too... that's why the VACUUM FULL worked (if my
assumption is correct).
To check if this is the case, look for "idle in transaction" in your
process listing (ps auxww|grep "idle in transaction"). If you got one
(or more) of that, you found your problem. If not, hopefully others will
help you :-)
Cheers,
Csaba.