Re: Make autovacuum sort tables in descending order of xid_age

On 12/12/19 1:35 PM, Mark Dilger wrote:
>   Let C = 1.00000002065
>   Let x = xid_age for a table
>   Let v = clamp(n_dead_tuples / reltuples*2) to max 0.5
>   Let a = clamp(changes_since_analyze / reltuples) to max 0.5
>
>   Let score = C**x + v + a

I should hasten to add that this is just a proof of concept
formula, not one that I'm specifically advocating. The point
is that we can devise a scoring system in which the xid age
is the dominant factor whenever it could possibly matter,
while still letting other factors prevail when xid age is
of little consequence.

--
Mark Dilger