Wojciech Strzałka <wstrzalka@gmail.com> writes:
>> To make that happen would require (at least) a full table scan. I think
>> most people are more interested in DROP COLUMN being a cheap operation
>> than in having the space be reclaimed quickly.
>> For a comparison point: large field values that don't happen to get
>> toasted don't vanish immediately, either.
> I agree DROP COLUMN should be cheap and I don't really expect it to happend immediately,
> but shouldn't VACUUM FULL clean it up?
No, changing the content of existing tuples is outside VACUUM's purview.
FWIW, I believe that a CLUSTER would clean it up, and would likely be
faster than a VACUUM FULL anyway.
regards, tom lane