Re: What's canceling autovacuum tasks?

Herouth Maoz <herouth@unicell.co.il> writes:
> Indeed autovacuum started working on some of the tables. At least one of these tables was one that I have trimmed up
usingCLUSTER. So I was watching that autovacuum process carefully. And then suddenly it was gone, after working for
20-oddhours. And I had even more dead tuples in pg_stat_user_tables for that table than before. 

> Looking at the log, I get this:

> 2011-02-06 15:21:42 IST ERROR:  canceling autovacuum task
> 2011-02-06 15:21:42 IST CONTEXT:  automatic vacuum of table "reports.alerts.smsq__archive"

> Why?

Most likely, some other session requested an exclusive lock on the
table.  Autovacuum will quit to avoid blocking the other query.

            regards, tom lane