Обсуждение: 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