Hi,
you're right, VACUUM FULL recovered the space, completely.
So, at this point I'm worried about my needs.
I cannot issue vacuum full as I read it locks the table.
In my DB, I (would) need to have a table with one bigint id field+ 10 bytea fields, 100 bytes long each (more or less, not fixed).
5/10000 rows maximum, but let's say 5000.
As traffic I can suppose 10000 updates per row per day (spread over groups of hours; each update involving two of those fields, randomly.
Also rows are chosen randomly (in my test I used a block of 2000 just to try one possibility).
So, it's a total of 50 millions updates per day, hence (50millions * 100 bytes *2 fields updated) 10Gbytes net per day.
I'm afraid it's not possible, according to my results.
Reagrds
Pupillo