Thread: exponentia​l performanc​e decrease, problem with version postgres + RHEL?

exponentia​l performanc​e decrease, problem with version postgres + RHEL?

From
John Nash
Date:
Hello everybody,

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.

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?

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?


Any idea would be great!

Thanks very much!!!!




Useful data:

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
 synchronous_commit       | on
 TimeZone                 | Europe/Madrid
 wal_buffers              | 64kB
 wal_sync_method          | fsync
(22 rows)


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

From
Nikolay Ulyanitsky
Date:
Hi

On 28 September 2012 13:43, John Nash <postgres.dba.needs.help@gmail.com> wrote:

> We don't understand why in here it's written "(Red Hat 4.4.6-3)".

GCC version is 4.4.6-3 on RHEL 6.2 :)

--
With best regards,
Nikolay


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

Ah ok!

Thank you very much!

 As it's written:

 compiled by gcc (GCC) 4.4.6 20110731

we thought that was the gcc version and the one written between () was
the OS version.

So, this is not a problem!

Thank you!!!!



2012/9/28 Nikolay Ulyanitsky <lystor@gmail.com>:
> Hi
>
> On 28 September 2012 13:43, John Nash <postgres.dba.needs.help@gmail.com> wrote:
>
>> We don't understand why in here it's written "(Red Hat 4.4.6-3)".
>
> GCC version is 4.4.6-3 on RHEL 6.2 :)
>
> --
> With best regards,
> Nikolay
>
>
> --
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