Hi, I am following this very interesting thread.
>From the documentation https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-IDLE-IN-TRANSACTION-SESSION-TIMEOUT, the 0 value will disable the timeout (not -1). On Wed, Jun 5, 2024 at 8:25 AM sud <suds1...@gmail.com> wrote: > Hello Laurenz, > > Thank you so much.This information was really helpful for us > understanding the working of these parameters. > > One follow up question i have , as we are setting one of the > standby/replica with value idle_in_transaction_session_timeout=-1 which can > cause the WAL's to be heavily backlogged in a scenario where we have a > query running for very long time on that instance. So in that case will > there be chances of instance restart and if that can be avoided anyway? > > And the plan is to set these system parameters with different values in > writer/read replica , so in that case if we apply the "alter system" > command on the primary , won't the WAL going to apply those same commands > forcibly on reader instance making those same as the writer instance > configuration( but we want the reader replica configuration to be different > from writer)? > > Appreciate your guidance. > > On Wed, May 29, 2024 at 1:38 PM Laurenz Albe <laurenz.a...@cybertec.at> > wrote: > >> On Wed, 2024-05-29 at 01:34 +0530, yudhi s wrote: >> > > The only way you can have no delay in replication AND no canceled >> queries is >> > > if you use two different standby servers with different settings for >> > > "max_standby_streaming_delay". One of the server is for HA, the >> other for >> > > your long-running queries. >> > >> > When you suggest having different max_standby_streaming_delay for first >> replica >> > (say 10 sec for High availability) and second replica(say -1 for long >> running queries). >> > Do you also suggest keeping "hot_feedback_standby" as "OFF" for all >> the three >> > instances i.e. master and both the replicas? >> >> The parameter is ignored on the master. >> It needs to be off on the standby that is running long queries. >> For the other standby it probably doesn't matter if you are not running >> any >> queries on it. I would leave "hot_standby_feedback = off" there as well. >> >> Actually, I would set "hot_standby = off" on the standby that is only used >> for HA. >> >> >> - I would leave "hot_standby_feedback" off everywhere. >> - "max_standby_streaming_delay" should be -1 on the reporting standby and >> very >> low or 0 on the HA standby. It doesn't matter on the primary. >> - "statement_timeout" should be way lower on the first two nodes. >> - "idle_in_transaction_session_timeout" is good. >> - I would leave "autovacuum_freeze_max_age" at the default setting but >> 100 million >> is ok too. >> >> Yours, >> Laurenz Albe >> >
