On Fri, 14 Apr 2023 at 09:47, Jonathan S. Katz <jk...@postgresql.org> wrote: > > Let me restate [1] in a different way. > > Using a large enough dataset, I did qualitatively look at overall usage > of both "vacuum_defer_cleanup_age" and compared to > "hot_standby_feedback", given you can use both to accomplish similar > outcomes.
I assume people would use hot_standby_feedback if they have streaming replication. The main use cases for vacuum_defer_cleanup_age would be if you're replaying WAL files. That may sound archaic but there are plenty of circumstances where your standby may not have network access to your primary at all or not want to be replaying continuously. I wonder whether your dataset is self-selecting sites that have streaming replication. That does seem like the more common usage pattern. Systems using wal files are more likely to be things like data warehouses, offline analytics systems, etc. They may not even be well known in the same organization that runs the online operations -- in my experience they're often run by marketing or sales organizations or in some cases infosec teams and consume data from lots of sources. The main reason to use wal archive replay is often to provide the isolation so that the operations team don't need to worry about the impact on production and that makes it easy to forget these even exist. -- greg
