Re: Should a DB vacuum use up a lot of space ?

[John R Pierce <pierce@xxxxxxxxxxxx>]

On 8/7/2016 10:26 AM, Philippe Girolami wrote:

More weirdness this afternoon : the wraparound ERROR showed up again even though I have trouble believing I burned through so many transactions in under a day. But let’s assume I did, here is what I noticed

1) I vacuumed all other databases. For everyone of those, the age went down to 50M instead of zero. Is that normal ?
2) The only database that didn’t work on was template0 (the age did not change). It did work on template1

Should I suspect something fishy going on ?

do you have any long running 'idle in transaction' sessions?  these would show up in pg_stat_activity, you want to look at now()-xact_start to see the age of the oldest of these.    no tuples newer than the oldest xact_start can be vacuumed.

select * from pg_stat_activity where state='idle in transaction';

select count(*), max(now()-xact_start) from pg_stat_activity where state='idle in transaction';

-- 
john r pierce, recycling bits in santa cruz