With a scale factor of 0.2, autovacuum won't kick in until there are an estimated 0.2 * 71M = 14.2M dead tuples. For such large tables, it may be prudent to adjust the autovacuum parameters to have a lower scale factor. You can also set the scale factor to zero, and then the threshold alone determines when autovacuum runs: you'd set the threshold to some number much larger than the default 50.
On Mon, Aug 28, 2017 at 11:45 AM Don Seiler <don@seiler.us> wrote:
PostgreSQL 9.2.18. I have a table with 71M rows (via select count). In pg_stat_activity, n_live_tups is 170K, n_dead_tups is slightly more than that (203K). The autovacuum parameter is on, the scale factor is 0.2 (default) and threshold is 50 (default), autovacuum_max_workers is 3. There are no custom autovacuum thresholds set for this table. The last_autovacuum field is null.
Obviously I would expect autovacuum/autoanalyze to kick in for this table so the stats aren't getting so far out of whack from reality. When I query pg_stat_activity, I never see any autovacuum jobs running, so it isn't a matter of too much work from what I can tell.
Previously I had tables not being autovacuumed because of index corruption (which would also cause manual vacuum to fail), but I was just able to successfully vacuum this table manually and now pg_stat_activity show the accurate info.
Wondering why my autovacuum daemon appears to be acting lazily?