On 2016-05-06 18:31:03 -0300, Alvaro Herrera wrote: > I don't know what happens when the freeze_table_age threshold is > reached.
We scan all non-frozen pages, whereas we earlier had to scan all pages. That's really both the significant benefit, and the danger. Because if we screw up the all-frozen bits in the visibilitymap, we'll be screwed soon after. > Do we scan the whole table when that happens? No, there's atm no way to force a whole-table vacuum, besides manually rm'ing the _vm fork. > Another question on this feature is what happens with the table age > (relfrozenxid, relminmxid) when the table is not wholly scanned by > vacuum. Basically we increase the horizons whenever scanning all pages that are not known to be frozen (+ potentially some frozen ones due to the skipping logic). Without that there'd really not be a point in the freeze map feature, as we'd continue to have the expensive anti wraparound vacuums. Andres -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers