On Sat, Mar 26, 2011 at 4:17 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Maxim Boguk" <Maxim.Boguk@gmail.com> writes:
> > In my case vacuum tried to truncate last 10-15GB from 100Gb relation, and
> > each time (3) it was cost 10+ minutes of service downtime (because that
> > table was completely locked).
>
> > Is that correct behaviour? Are here any way to speedup that process or
> at
> > least allow read-only queries during that time?
>
> Use autovacuum --- if there's something that wants to access the table,
> autovac will get kicked off the lock. (Of course, the table may never
> get truncated then, but maybe you don't care.)
>
> regards, tom lane
>
Thank you for an idea.
Are having lots empty pages at end of the table can have any negative impact
on database performance (assuming I have plenty of free disk space)?
In my case these 100Gb table going to be reduced to 20Gb size actual data
located at start of the table, so I worry about possible negative impact of
having extra 80Gb free space at end of the table.
Regards,
Maxim