Re: vacuum does not reclaim rows

> > Does anybody know why vacuum full does not relcaim deleted rows if a
> > open transaction which started before the deletion happens is running
> > even on a different database?
> 
> On what do you base that it doesn't reclaim those rows?

test=# vacuum full verbose t1;
INFO:  --Relation public.t1--
INFO:  Pages 1: Changed 1, reaped 0, Empty 0, New 0; Tup 1: Vac 0, Keep/VTL 1/0, UnUsed 0, MinLen 32, MaxLen 32;
Re-using:Free/Avail. Space 8136/8136; EndEmpty/Avail. Pages 0/1.       CPU 0.00s/0.00u sec elapsed 0.00 sec.
 
INFO:  Rel t1: Pages: 1 --> 1; Tuple(s) moved: 0.       CPU 0.00s/0.00u sec elapsed 0.00 sec.
VACUUM

Here you can see "Pages: 1 --> 1; Tuple(s) moved: 0", it indicates
vacuum actually skips the table and does not reclaim those rows.

Here is a case when vacuum does reclaim.

test=# vacuum full verbose t1;
INFO:  --Relation public.t1--
INFO:  Pages 1: Changed 0, reaped 1, Empty 0, New 0; Tup 0: Vac 1, Keep/VTL 0/0, UnUsed 0, MinLen 0, MaxLen 0;
Re-using:Free/Avail. Space 8168/0; EndEmpty/Avail. Pages 1/0.       CPU 0.00s/0.00u sec elapsed 0.00 sec.
 
INFO:  Rel t1: Pages: 1 --> 0.
VACUUM
--
Tatsuo Ishii