On Sat, Mar 21, 2020 at 01:44:47AM -0400, Rui DeSousa wrote: > > > > On Mar 20, 2020, at 5:50 PM, Kurt Roeckx <kurt@xxxxxxxxx> wrote: > > > > Hi, > > > > I have a few tables that are append only. Thre are only gets insert > > and select queries, never update or delete. > > > > What I see is that every file is still being updated. It's > > currently about 500 GB big, and every of that almost 500 files has > > been touched the past 24 hours. > > > > (auto) vacuum is not happening on the table. > > > > Vacuum is still required as the tuples need to be frozen. Have you vacuumed the table? I did not manually vacuum them, nor did auto vacuum ever get triggered, at least not according to what is in pg_stat_user_tables; > It could be the result of records being frozen during selects statements; select can freeze tuples that meet the criteria for being frozen. I guess it's doing that now. iotop shows: TID PRIO USER DISK READ> DISK WRITE SWAPIN IO COMMAND 10227 be/4 postgres 67.68 G 67.56 G 0.00 % 79.66 % postgres: 12/main: kurt certs [local] VACUUM > I would recommend vacuuming the table to get the existing records frozen; then I believe you should see fewer updates to the all the base files. If this is needed, why doesn't autovacuum do this for me? Or do I need to modify some parameters so that autovacuum does get triggered? I actually didn't run any select query on that table yet, it's still importing the data. Can an insert also trigger the freeze? Anyway, the vacuum is running, I will let you know if it helps or not. Kurt
