Re: Considerable performance downgrade of v11 and 12 on Windows - Mailing list pgsql-performance

Laurenz,
There is no way to run copy without the "type" on v11. See this thread
https://www.postgresql.org/message-id/CAKHmqNCfTMM6%3DPqc6RUMEQ_2BPfo5KGGG-0fzRXZCVooo%3DwdNA%40mail.gmail.com

My machine is running on NVMe disks, so the I/O subsystem very strong.
The 100% overload is not constant but periodical, as if there are some
kind of dumps for recovery performed in the background.

maintenance_work_mem is the same in both cases.

Regards

пт, 29 нояб. 2019 г. в 15:04, Laurenz Albe <laurenz.albe@cybertec.at>:
>
> On Fri, 2019-11-29 at 13:04 +0300, Eugene Podshivalov wrote:
> > I'm using PostgreSQL on Windows for Planet OSM database and have
> > noticed considirable decrease in performance when upgrading from v10
> > to 11 or 12. Here are the details of the experiment I conducted trying
> > to figure out what is causing the issue.
> >
> > Installed PostgreSQL 10 from scratch. Created a database and a table.
> > [...]
> > SET synchronous_commit TO OFF;
> > COPY ways FROM 'E:\ways.txt';
> > ALTER TABLE ONLY ways ADD CONSTRAINT pk_ways PRIMARY KEY (id);
> >
> > The file is 365GB in size.
> >
> > The copy operation took 3.5h and the resulting table size is 253GB.
> > The primary key operation took 20 minutes and occuped 13GB of disk
> > space.
> >
> > Then I unstalled PostgreSQL v10, deleted the data directory and
> > installed v11 from scratch. Created the same kind of database and
> > table. v11 is not able to handle large files, so the I piped the data
> > through the cmd type command, and then added the primary key with the
> > same command as above. synchronous_commit turned off beforehand as
> > above.
> >
> > COPY ways FROM PROGRAM 'cmd /c "type E:\ways.txt"';
> >
> > The copy operation took 7 hours and adding primary key took 1h 40m !
> > The resulting table and pk sizes are the same as in v10. Also very
> > high load on disk drive (quite often at 100%) was observed.
> >
> > v12 performs the same as v11.
> >
> > Here are the changes in v11 default postgresql.conf file compared to
> > v10 one. Differences in Authentication, Replication and Logging
> > sections are skipped.
> >
> > -#replacement_sort_tuples = 150000
> > +#max_parallel_maintenance_workers = 2
> > +#parallel_leader_participation = on
> > ~max_wal_size = 1GB     (in v10 is commented out)
> > ~min_wal_size = 80MB    (in v10 is commented out)
> > +#enable_parallel_append = on
> > +#enable_partitionwise_join = off
> > +#enable_partitionwise_aggregate = off
> > +#enable_parallel_hash = on
> > +#enable_partition_pruning = on
> > +#jit_above_cost = 100000
> > +#jit_inline_above_cost = 500000
> > +#jit_optimize_above_cost = 500000
> > +#jit = off
> > +#jit_provider = 'llvmjit'
> > +#vacuum_cleanup_index_scale_factor = 0.1
> >
> > Any ideas pleaes on what is trapping the performance?
>
> Seems like you have a very weak I/O subsystem.
>
> For the COPY, try doing it the same way in both cases (without the "type").
>
> For the index creation, perhaps set "max_parallel_maintenance_workers = 0"
> so that your system doesn't get overloaded.
>
> Is "maintenance_work_mem" set to the same value in both cases?
>
> Yours,
> Laurenz Albe
> --
> Cybertec | https://www.cybertec-postgresql.com
>