There are not that many tables, 175. There are a decent number of transactions on the database, 35k a second during the day. I ran a vacuum verbose on table1 today and got this output on the pages frozen.
frozen: 2813436 pages from table (0.70% of total) had 7028123 tuples frozen On Fri, Jan 31, 2025 at 5:46 PM Peter Geoghegan <p...@bowt.ie> wrote: > On Fri, Jan 31, 2025 at 5:28 PM Joshua Banton <bant...@gmail.com> wrote: > > The issue mostly manifests near the end of the "scanning heap" phase of > vacuuming of one of our largest tables, we'll call table1. RDS Performance > Insights reports that selects on table1 start to wait on cpu, where > previously it didn't even show up in the top 25 queries by wait. It doesn't > always happen, but if there is a larger than usual number of selects on > table1 it is more likely to happen. > > Does this database also have many tables? As in thousands of tables? > > I am reminded of this issue: > > > https://www.postgresql.org/message-id/flat/da3205c4-5b07-a65c-6c26-a293c6464fdb%40postgrespro.ru > > I've heard of this happening when an aggressive VACUUM updates > relfrozenxid on a larger table. > > -- > Peter Geoghegan >
