Transaction Wraparound Help-Understanding

Hello,

I'm trying to understand why autovacuum runs to prevent wraparound on
tables that should be static and don't change. For example, we have tables,
in one of our databases, that get created every day. Those tables are then
actively updated throughout the day. Once a new day begins, a new table is
created for that days data. The previous days table is no longer changed or
updated and used for historical queries only.

So, the way I understand transaction wrap around, I would think the only
table needing vacuuming to prevent wraparound, would be the active table?
But, I also notice the older
tables getting vacuumed to prevent wrap around as well. Can someone help me
understand this?

Here is an example:

30551 tracks None local 2.6 0.1 31.81M 0.00B
01:51.58 N N active autovacuum: VACUUM
public.fused_xyz20191222 (to prevent wraparound)
34151 tracks None local 5.5 0.1 29.96M 2.61K
01:13.31 N N active autovacuum: VACUUM
public.fused_xyz20191119 (to prevent wraparound)
34613 tracks None local 2.3 0.1 29.67M 0.00B
01:07.83 N N active autovacuum: VACUUM
public.fused_xyz20191128 (to prevent wraparound)
39686 tracks None local 2.9 0.0 29.67M 0.00B
00:09.00 N N active autovacuum: VACUUM
public.fused_xyz20200112 (to prevent wraparound)

The tables listed above are static at this point, but as you can see, they
are actively being vacuumed to prevent wraparound.

Thanks,

Jay

--

Jerome Talbert

Senior IT Infrastructure Engineer

PASSUR Aerospace, Inc.

O: 407-205-0688

C: 407-619-9868

jtalbert(at)passur(dot)com