Re: [External] Re: Slot issues
What was the whole point of this divergence :) We use replication slots and it is for this reason we are able to scale our applications by redirecting reads and writes backed by haproxy and pgbouncer. with the health check of replication lag. It works awesome and at a much much lower cost to what aws used to charge us for. (1 master, 3 slaves .. that goes to 7-8 during peak days) With the use of logical replication we were able to create a multimaster mesh that allowed the writes to certain tables across the ocean and all regions subscribed to it. As a result, at any given time all 5 availability. Zones had same data and we would sustain an occasional WAN outage between two DCs. We use around 300 Postgres servers, everything managed via puppet and foreman. And I have not seen any single issue w r t the one reported for any of our setups. So I guess it is generalising just based out of some threads :) I do not use db2 but there has never been a need for one in my company as we have multiple design patterns of Postgres architecture based of requirements. On Mon, 15 Oct 2018 at 3:46 AM Ravi Krishna wrote: > > > > You're not forced to use slots. Their purpose is to allow to force the > > primary to keep necessary resources around. Which also allows to get rid > > of the archive in some setups. > > Thanks. > > Disclaimer: We don't use replication as we piggy back on AWS HA. > > The reason why I posted this is because majority of replication related > messages in this forum > is about slots :-) -- Regards, Vijay
Re: [External] Re: Slot issues
ah that explains. Thanks andres. I do not use rsync, hence was not able to reproduce i guess :) Regards, Vijay On Mon, Oct 15, 2018 at 2:46 AM bhargav kamineni wrote: > Yeah i have used rsync , Got it now will increase the > max_replication_slots to high enough , Thank you Andres Freund :-) > > On Mon, 15 Oct 2018 at 02:40, Andres Freund wrote: > >> Hi, >> >> Please try to quote properly. >> >> On 2018-10-15 01:57:53 +0530, bhargav kamineni wrote: >> > I got his on standby, could you please explain in detail about >> > --*but that *on the standby* haven't set max_replication_slots high >> enough* >> > . >> >> What is max_replication_slots set to on the new standby? >> >> If you created the new basebackup using rsync, and didn't exclude >> pg_replication_slot, it'll have copied the slots from the primary. And >> thus needs a high enough max_replication_slots to work with them. >> >> - Andres >> >
Re: [External] Re: Slot issues
Sorry Bhargav. I tried to simulate the scenarios, 3 node cluster 1primary, 2hot standby given: max_replication_slots = 2 on primary, and i try to create 2 hot standby -> runs fine. max_replication_slots = 1 on primary, and i try to create 2 hot standby -> gives PANIC, increase replication slots. (the standby only cries with replication slot does not exist, not increase number of replication slots) max_replication_slots = 2 on primary, and max_replication_slots=1 on hot standby, delete recovery.conf and recover from pg_baseback works fine. max_replication_slots = 2 on primary, on standby i try to use a replication_slot already existing, it gives correct error of slot in use and not increase replication slot error. my pg_replslot folder is consistent of the replication slots i have on the master. so i guess, i'll leave it to the experts. but i still do not understand why would you get that error on standby, unless you are doing cascading replication. I'll watch this thread to see how this is resolved. Thanks, Vijay Regards, Vijay On Mon, Oct 15, 2018 at 2:41 AM Andres Freund wrote: > Hi, > > Please try to quote properly. > > On 2018-10-15 01:57:53 +0530, bhargav kamineni wrote: > > I got his on standby, could you please explain in detail about > > --*but that *on the standby* haven't set max_replication_slots high > enough* > > . > > What is max_replication_slots set to on the new standby? > > If you created the new basebackup using rsync, and didn't exclude > pg_replication_slot, it'll have copied the slots from the primary. And > thus needs a high enough max_replication_slots to work with them. > > - Andres > >
Re: [External] Re: Slot issues
pg_replslot # ls -lrth total 4.0K drwx-- 2 postgres postgres 4.0K Oct 14 14:55 replication_slot On Mon, 15 Oct 2018 at 02:11, Vijaykumar Jain wrote: > ok wait, you data directory path may be different :) > i mean wherever your pg data dir is, from there find pg_replslot folder > and list the contents of it. > > Regards, > Vijay > > > On Mon, Oct 15, 2018 at 2:10 AM Vijaykumar Jain > wrote: > >> i guess he is trying to confirm if the value of max_replication_slot is >> the same on all the master and the standby nodes. >> >> also, >> >> I am trying to shoot in the dark. >> >> can you give the output of (on master) >> ls /var/lib/postgresql//main/pg_replslot/* >> >> also the value of max_replication_slot on the master and all the >> standby's. >> also, how are you creating the replication slot? >> >> can you share the query? >> >> also pls share the content of the recovery.conf on the standby nodes >> (both currently running and currently not running). >> you can scribble company secret stuff. >> >> >> Regards, >> Vijay >> >> >> On Mon, Oct 15, 2018 at 1:58 AM bhargav kamineni < >> bhargavpostg...@gmail.com> wrote: >> >>> I got his on standby, could you please explain in detail about >>> --*but that *on the standby* haven't set max_replication_slots high >>> enough*. >>> >>> Thanks, >>> Bhargav >>> >>> On Mon, 15 Oct 2018 at 01:50, Andres Freund wrote: >>> Hi, On 2018-10-15 00:15:53 +0530, bhargav kamineni wrote: > Hi Team, > > I am getting this ERROR while starting my second slave server > > PANIC: too many replication slots active before shutdown > HINT: Increase max_replication_slots and try again. > > max_replication_slots on my master is 2 and one of them is already active > for another slave, > do i need to increase this parameter for the need of working of another > slave ? if so whats the reason ? You're getting that error on the standby, not the primary, right? In all likelihood the problem is that you copied over replication slots to your standby server, but that *on the standby* haven't set max_replication_slots high enough. Greetings, Andres Freund >>>
Re: [External] Re: Slot issues
ok wait, you data directory path may be different :) i mean wherever your pg data dir is, from there find pg_replslot folder and list the contents of it. Regards, Vijay On Mon, Oct 15, 2018 at 2:10 AM Vijaykumar Jain wrote: > i guess he is trying to confirm if the value of max_replication_slot is > the same on all the master and the standby nodes. > > also, > > I am trying to shoot in the dark. > > can you give the output of (on master) > ls /var/lib/postgresql//main/pg_replslot/* > > also the value of max_replication_slot on the master and all the standby's. > also, how are you creating the replication slot? > > can you share the query? > > also pls share the content of the recovery.conf on the standby nodes (both > currently running and currently not running). > you can scribble company secret stuff. > > > Regards, > Vijay > > > On Mon, Oct 15, 2018 at 1:58 AM bhargav kamineni < > bhargavpostg...@gmail.com> wrote: > >> I got his on standby, could you please explain in detail about >> --*but that *on the standby* haven't set max_replication_slots high >> enough*. >> >> Thanks, >> Bhargav >> >> On Mon, 15 Oct 2018 at 01:50, Andres Freund wrote: >> >>> Hi, >>> >>> On 2018-10-15 00:15:53 +0530, bhargav kamineni wrote: >>> > Hi Team, >>> > >>> > I am getting this ERROR while starting my second slave server >>> > >>> > PANIC: too many replication slots active before shutdown >>> > HINT: Increase max_replication_slots and try again. >>> > >>> > max_replication_slots on my master is 2 and one of them is already >>> active >>> > for another slave, >>> > do i need to increase this parameter for the need of working of another >>> > slave ? if so whats the reason ? >>> >>> You're getting that error on the standby, not the primary, right? In >>> all likelihood the problem is that you copied over replication slots to >>> your standby server, but that *on the standby* haven't set >>> max_replication_slots high enough. >>> >>> Greetings, >>> >>> Andres Freund >>> >>
Re: [External] Re: Slot issues
i guess he is trying to confirm if the value of max_replication_slot is the same on all the master and the standby nodes. also, I am trying to shoot in the dark. can you give the output of (on master) ls /var/lib/postgresql//main/pg_replslot/* also the value of max_replication_slot on the master and all the standby's. also, how are you creating the replication slot? can you share the query? also pls share the content of the recovery.conf on the standby nodes (both currently running and currently not running). you can scribble company secret stuff. Regards, Vijay On Mon, Oct 15, 2018 at 1:58 AM bhargav kamineni wrote: > I got his on standby, could you please explain in detail about > --*but that *on the standby* haven't set max_replication_slots high > enough*. > > Thanks, > Bhargav > > On Mon, 15 Oct 2018 at 01:50, Andres Freund wrote: > >> Hi, >> >> On 2018-10-15 00:15:53 +0530, bhargav kamineni wrote: >> > Hi Team, >> > >> > I am getting this ERROR while starting my second slave server >> > >> > PANIC: too many replication slots active before shutdown >> > HINT: Increase max_replication_slots and try again. >> > >> > max_replication_slots on my master is 2 and one of them is already >> active >> > for another slave, >> > do i need to increase this parameter for the need of working of another >> > slave ? if so whats the reason ? >> >> You're getting that error on the standby, not the primary, right? In >> all likelihood the problem is that you copied over replication slots to >> your standby server, but that *on the standby* haven't set >> max_replication_slots high enough. >> >> Greetings, >> >> Andres Freund >> >
