Re: Postgres auto vacuum - Disable
Hi Again, Is there any difference in the way vacuum is handled in postgres9.6 and postgres12.9, We are noticing the below issue of waiting process only after upgrading to postgres12.5 $ ps -ef | grep 'waiting' postgres 8833 62646 0 Jul28 ?00:00:00 postgres: postgres cgms [local] VACUUM waiting postgres 18437 62646 0 Jul27 ?00:00:00 postgres: postgres cgms [local] VACUUM waiting Regards, Karthik From: Julien Rouhaud Date: Monday, 7 November 2022 at 7:06 PM To: Laurenz Albe Cc: Karthik Jagadish (kjagadis) , Dave Page , pgsql-hack...@postgresql.org , Chandruganth Ayyavoo Selvam (chaayyav) , Prasanna Satyanarayanan (prassaty) , Jaganbabu M (jmunusam) , Joel Mariadasan (jomariad) Subject: Re: Postgres auto vacuum - Disable Hi, On Mon, Nov 07, 2022 at 02:22:56PM +0100, Laurenz Albe wrote: > On Mon, 2022-11-07 at 12:12 +, Karthik Jagadish (kjagadis) wrote: > > I have follow-up question where the vacuum process is waiting and not doing > > it’s job. > > When we grep on waiting process we see below output. Whenever we see this > > we notice > > that the vacuum is not happening and the system is running out of space. > > > > [root@zpah0031 ~]# ps -ef | grep 'waiting' > > postgres 8833 62646 0 Jul28 ?00:00:00 postgres: postgres cgms > > [local] VACUUM waiting > > postgres 18437 62646 0 Jul27 ?00:00:00 postgres: postgres cgms > > [local] VACUUM waiting > > > > > > What could be the reason as to why the vacuum is not happening? Is it > > because some lock is > > present in the table/db or any other reason? > > Look in "pg_stat_activity". I didn't check, but I'm sure it's the > intentional break > configured with "autovacuum_vacuum_cost_delay". Reduce that parameter for > more > autovacuum speed. Really? An autovacuum should be displayed as "autovacuum worker", this looks like plain backends to me, where an interactive VACUUM has been issued and is waiting on a heavyweight lock.
Re: Postgres auto vacuum - Disable
Hi, On Mon, Nov 07, 2022 at 02:22:56PM +0100, Laurenz Albe wrote: > On Mon, 2022-11-07 at 12:12 +, Karthik Jagadish (kjagadis) wrote: > > I have follow-up question where the vacuum process is waiting and not doing > > it’s job. > > When we grep on waiting process we see below output. Whenever we see this > > we notice > > that the vacuum is not happening and the system is running out of space. > > > > [root@zpah0031 ~]# ps -ef | grep 'waiting' > > postgres 8833 62646 0 Jul28 ? 00:00:00 postgres: postgres cgms > > [local] VACUUM waiting > > postgres 18437 62646 0 Jul27 ? 00:00:00 postgres: postgres cgms > > [local] VACUUM waiting > > > > > > What could be the reason as to why the vacuum is not happening? Is it > > because some lock is > > present in the table/db or any other reason? > > Look in "pg_stat_activity". I didn't check, but I'm sure it's the > intentional break > configured with "autovacuum_vacuum_cost_delay". Reduce that parameter for > more > autovacuum speed. Really? An autovacuum should be displayed as "autovacuum worker", this looks like plain backends to me, where an interactive VACUUM has been issued and is waiting on a heavyweight lock.
Re: Postgres auto vacuum - Disable
On Mon, 2022-11-07 at 12:12 +, Karthik Jagadish (kjagadis) wrote: > I have follow-up question where the vacuum process is waiting and not doing > it’s job. > When we grep on waiting process we see below output. Whenever we see this we > notice > that the vacuum is not happening and the system is running out of space. > > [root@zpah0031 ~]# ps -ef | grep 'waiting' > postgres 8833 62646 0 Jul28 ? 00:00:00 postgres: postgres cgms > [local] VACUUM waiting > postgres 18437 62646 0 Jul27 ? 00:00:00 postgres: postgres cgms > [local] VACUUM waiting > > > What could be the reason as to why the vacuum is not happening? Is it because > some lock is > present in the table/db or any other reason? Look in "pg_stat_activity". I didn't check, but I'm sure it's the intentional break configured with "autovacuum_vacuum_cost_delay". Reduce that parameter for more autovacuum speed. Yours, Laurenz Albe
Re: Postgres auto vacuum - Disable
Hi, Thanks for the response. I have follow-up question where the vacuum process is waiting and not doing it’s job. When we grep on waiting process we see below output. Whenever we see this we notice that the vacuum is not happening and the system is running out of space. [root@zpah0031 ~]# ps -ef | grep 'waiting' postgres 8833 62646 0 Jul28 ?00:00:00 postgres: postgres cgms [local] VACUUM waiting postgres 18437 62646 0 Jul27 ?00:00:00 postgres: postgres cgms [local] VACUUM waiting What could be the reason as to why the vacuum is not happening? Is it because some lock is present in the table/db or any other reason? Regards, Karthik From: Dave Page Date: Monday, 7 November 2022 at 5:17 PM To: Karthik Jagadish (kjagadis) Cc: pgsql-hack...@postgresql.org , Chandruganth Ayyavoo Selvam (chaayyav) , Prasanna Satyanarayanan (prassaty) , Jaganbabu M (jmunusam) , Joel Mariadasan (jomariad) Subject: Re: Postgres auto vacuum - Disable Hi On Mon, 7 Nov 2022 at 11:42, Karthik Jagadish (kjagadis) mailto:kjaga...@cisco.com>> wrote: Hi, We have a NMS application in cisco and using postgres as a database. We have query related to disabling auto vacuum. We have below configuration in postgres.conf where the autovacuum=on is commented out. [ShapeDescription automatically generated] But when checked in database we notice that it’s showing as on [Graphical user interface, timelineDescription automatically generated] What would this mean? Does it mean that autovacuum is not disabled? Appreciate a response. Right. The default is for it to be enabled, so commenting out the option does nothing. You would need to set it explicitly to off. BUT... you almost certainly don't want to do that. Cases where it should be disabled are *extremely* rare. Make sure you *really* know what you're letting yourself in for by disabling autovacuum, and don't rely on 10+ year old performance tuning advice from random places on the internet, if that's what you're doing. -- Dave Page Blog: https://pgsnake.blogspot.com Twitter: @pgsnake EDB: https://www.enterprisedb.com
Re: Postgres auto vacuum - Disable
Hi On Mon, 7 Nov 2022 at 11:42, Karthik Jagadish (kjagadis) wrote: > Hi, > > > > We have a NMS application in cisco and using postgres as a database. > > > > We have query related to disabling auto vacuum. We have below > configuration in postgres.conf where the autovacuum=on is commented out. > > > > [image: Shape Description automatically generated] > > > > But when checked in database we notice that it’s showing as on > > > > [image: Graphical user interface, timeline Description automatically > generated] > > > > What would this mean? Does it mean that autovacuum is not disabled? > Appreciate a response. > Right. The default is for it to be enabled, so commenting out the option does nothing. You would need to set it explicitly to off. BUT... you almost certainly don't want to do that. Cases where it should be disabled are *extremely* rare. Make sure you *really* know what you're letting yourself in for by disabling autovacuum, and don't rely on 10+ year old performance tuning advice from random places on the internet, if that's what you're doing. -- Dave Page Blog: https://pgsnake.blogspot.com Twitter: @pgsnake EDB: https://www.enterprisedb.com
Postgres auto vacuum - Disable
Hi, We have a NMS application in cisco and using postgres as a database. We have query related to disabling auto vacuum. We have below configuration in postgres.conf where the autovacuum=on is commented out. [Shape Description automatically generated] But when checked in database we notice that it’s showing as on [Graphical user interface, timeline Description automatically generated] What would this mean? Does it mean that autovacuum is not disabled? Appreciate a response. Regards, Karthik
