On Mon, Mar 22, 2021 at 8:28 PM Peter Geoghegan <p...@bowt.ie> wrote: > You seem to be concerned about a similar contradiction. In fact it's > *very* similar contradiction, because this new GUC is naturally a > "sibling GUC" of both vacuum_freeze_table_age and > autovacuum_vacuum_max_age (the "units" are the same, though the > behavior that each GUC triggers is different -- but > vacuum_freeze_table_age and autovacuum_vacuum_max_age are both already > *similar and different* in the same way). So perhaps the solution > should be similar -- silently interpret the setting of the new GUC to > resolve the contradiction.
More concretely, maybe the new GUC is forced to be 1.05 of vacuum_freeze_table_age. Of course that scheme is a bit arbitrary -- but so is the existing 0.95 scheme. There may be some value in picking a scheme that "advertises" that all three GUCs are symmetrical, or at least related -- all three divide up the table's XID space. -- Peter Geoghegan
