RE: [PERFORM] exponentia​l performanc​e decrease, problem with version postgres + RHEL?

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От Albe Laurenz
Тема RE: [PERFORM] exponentia​l performanc​e decrease, problem with version postgres + RHEL?
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Msg-id D960CB61B694CF459DCFB4B0128514C2087E2DC1@exadv11.host.magwien.gv.at
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Ответ на exponentia​l performanc​e decrease, problem with version postgres + RHEL?  (John Nash <postgres.dba.needs.help@gmail.com>)
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John Nash wrote:
> We have being doing some testing with an ISD transaction and we had
> some problems that we posted here.
> 
> The answers we got were very kind and useful but we couldn't solve the problem.

Could you refer to the threads so that you don't get the same advice again?

> We have doing some investigations after this and we are thinking if is
> it possible that OS has something to do with this issue. I mean, we
> have two hosts, both of them with OS = Red Hat Enterprise Linux Server
> release 6.2 (Santiago)
> 
> But when doing "select * from version()" on the postgres shell we obtain:
> 
> sessions=# select * from version();
>                                                    version
> ------------------------------------------------------------------------------------------------------
> --------
>  PostgreSQL 9.1.3 on x86_64-unknown-linux-gnu, compiled by gcc (GCC)
> 4.4.6 20110731 (Red Hat 4.4.6-3), 64-bit
> (1 row)
> 
> We don't understand why in here it's written "(Red Hat 4.4.6-3)".
> 
> Is it possible that we have installed a postgres' version that it's
> not perfect for the OS?

It means that the PostgreSQL you are using was compiled with a
compiler that was compiled on RHEL4.  Shouldn't be a problem.

> But if this is a problem, why are we obtaining a normal perform on a
> host and an exponential performance decrease on another?
> 
> And how can we obtain a normal performance when launching the program
> which does the queries from another host (remote url) but when
> launching it in the same host we obtain this decrease on the
> performance?

Try to identify the bottleneck.
Is it disk I/O, CPU, memory or something else?

> name           |
> current_setting
> 
> --------------------------+---------------------------------------------------------------------------
> -----------------
> ------------------
>  version                  | PostgreSQL 9.1.3 on
> x86_64-unknown-linux-gnu, compiled by gcc (GCC) 4.4.6 20110731 (Red
> Hat
>  4.4.6-3), 64-bit
>  archive_mode             | off
>  client_encoding          | UTF8
>  fsync                    | on
>  lc_collate               | en_US.UTF-8
>  lc_ctype                 | en_US.UTF-8
>  listen_addresses         | *
>  log_directory            | pg_log
>  log_filename             | postgresql-%a.log
>  log_rotation_age         | 1d
>  log_rotation_size        | 0
>  log_truncate_on_rotation | on
>  logging_collector        | on
>  max_connections          | 100
>  max_stack_depth          | 2MB
>  port                     | 50008
>  server_encoding          | UTF8
>  shared_buffers           | 32MB

Now that sticks out as being pretty small.
Try 1/4 of the memory available for the database, but not
more than 2 GB.

>  synchronous_commit       | on
>  TimeZone                 | Europe/Madrid
>  wal_buffers              | 64kB

That's also pretty small.

>  wal_sync_method          | fsync
> (22 rows)

Yours,
Laurenz Albe

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