On Tue, Jun 23, 2020 at 2:34 PM Jim Hurne <jhurne@xxxxxxxxxx> wrote:
Sure! Below are more of the details from the same set of logs. Looking at
them myself, I see that there is always some percentage of tuples that are
dead but are not yet removable. And that number increases on every vacuum,
which might explain in part why autovacuum elapsed times keep increasing.
What causes a dead tuple to be unremovable?
Here are a couple good write ups.
Long running transactions are the common one that I see. You might be dealing with replication slots or prepared transactions. Basically, if some process might see that "old truth", then it can't be vacuumed away yet.
