Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

Hi, the perf profiles look really weird - clearly, there's a lot of lock contention, because the top item is this 13.49%13.40% postmaster postgres [.] LWLockAcquire | ---LWLockAcquire That's a sign of lock contention - not sure which one,

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

Hello, any news ? Thank you, Alessandro. On Fri, Mar 23, 2018 at 8:22 PM, Alessandro Aste wrote: > PS , in the meanwhile I discovered a 2nd workaround(beside disabling > parallel processing) . I added offset 0 to the subquery , and, according > to the

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

PS , in the meanwhile I discovered a 2nd workaround(beside disabling parallel processing) . I added offset 0 to the subquery , and, according to the documentation, “OFFSET 0 is the same as omitting the OFFSET clause” - https://www.postgresql.org/docs/current/static/queries-limit.html cmd3dev=#

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

Thanks Tomas. We're currently building postgres from source. In order to enable symbols, you want me to re-configure postres with --enable-debug then run perf? Regards, On Thu, Mar 22, 2018 at 5:00 PM, Tomas Vondra wrote: > > > On 03/22/2018 11:33 AM, Alessandro

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

On 03/22/2018 11:29 PM, Alessandro Aste wrote: > Thanks Tomas. We're currently building postgres from source. In order to > enable symbols, you want me to re-configure postres with  --enable-debug > then run perf? > Yes. regards -- Tomas Vondra http://www.2ndQuadrant.com

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

On 03/22/2018 11:33 AM, Alessandro Aste wrote: > Tomas, thank you. This machine  is abare metal server running only a > staging postgresql 10.3  instance. Nobody is using it beside me.  > > I'm attaching 4 files.   > > every_30_seconds_top_stats_during_query.txt    - this is a caputure of >

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

Tomas, thank you. This machine is abare metal server running only a staging postgresql 10.3 instance. Nobody is using it beside me. I'm attaching 4 files. every_30_seconds_top_stats_during_query.txt- this is a caputure of the top command every 30 seconds(more or less) for 10+ minutes while

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

On 03/21/2018 08:44 PM, Alessandro Aste wrote: > Thanks for your reply Tomas.  The query just got stuck for forever.  I > observed no CPU spikes, it is currently running and I see 89 of the CPU > idle. I'm using a relative powerfull machine (120 GB ram, 56 CPU).   > That doesn't really answer

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

Thanks for your reply Tomas. The query just got stuck for forever. I observed no CPU spikes, it is currently running and I see 89 of the CPU idle. I'm using a relative powerfull machine (120 GB ram, 56 CPU). Plain analyze as requested. : QUERY PLAN

Re: Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

On 03/21/2018 05:09 PM, Alessandro Aste wrote: > Hi there, we are using postgresql 10.3 and we're facing an issue with a > query. The query (full query below)  completes only  when:  > > 1 - LIMIT 10 is removed > or > 2 -  show max_parallel_workers_per_gather  is set to 0, so parallel >

Postgresql 10.3 , query never completes if LIMIT clause is specified and paralle processing is on

Hi there, we are using postgresql 10.3 and we're facing an issue with a query. The query (full query below) completes only when: 1 - LIMIT 10 is removed or 2 - show max_parallel_workers_per_gather is set to 0, so parallel processing is disabled. With max_parallel_workers_per_gather set to