Re: nonremovable row versions

On Mon, Jun 8, 2009 at 12:28 AM, Lutz Steinborn<l(dot)steinborn(at)4c-ag(dot)de> wrote:
> Hi,
>
> can anybody tell me how to get rid of nonremovable row versions ?
> I know what those rows coming from long running transactions. But I can't see
> any long running transactions in pg_locks and all postgres processes are idle.
> How else can I check if transaction in process ?
>
>
> I don't have any idea from where those long running transaction are comming
> because we are stopping/starting our apllications every 2-3 days. And its not
> the nature of our applications to establish long running transactions.

I think you misunderstand nonremoveable rows. A demonstration:

postgres=# create table test (id int);
CREATE TABLE
postgres=# insert into test values (1),(2),(3);
INSERT 0 3
postgres=# vacuum verbose test;
INFO: vacuuming "public.test"
INFO: "test": found 0 removable, 3 nonremovable row versions in 1 pages
DETAIL: 0 dead row versions cannot be removed yet.
There were 0 unused item pointers.
1 pages contain useful free space.
0 pages are entirely empty.
CPU 0.00s/0.00u sec elapsed 0.00 sec.
VACUUM

It's not just old transactions, it's current data as well.

>
> We are using postgresql 8.1.4.

You really should be running 8.1.17.