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Strange behavior over WAN
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* Strange behavior over WAN
@ 2019-10-11 14:38 Albert Shih <Albert.Shih@obspm.fr>
  2019-10-11 19:04 ` Re: Strange behavior over WAN Fernando Hevia <fhevia@gmail.com>
  0 siblings, 1 reply; 2+ messages in thread

From: Albert Shih @ 2019-10-11 14:38 UTC (permalink / raw)
  To: pgsql-admin

Hi


We got a postgresql server with a very small database ( ~few Mo) and do
a extract with a ruby (sequel) client.

If I do the extract on the same server the speed is correct (10-30 sec)

If I do the extract on the same LAN the speed is correct. (10-30 sec)

If I do the extract from the wan the speed goes from slow to ultra-slow
(reach the TTL and sometime the connection are close) (1 minutes -> 8
minutes)

When this happen I try to see if they are some bandwith problem, and they
don't have any bandwith problem ( ~10-20Mbytes/s 120-180Mbits/s), the size
of the extraction (with tcpdump) are small (~2Mo).

I also check the fragmentation of the tcp flow, when I'm on the wan they
are x2 packets so I can understand they are slower than over the LAN but I
can see how it's possible to go 50-60x slower.

Any idea ? ....or solution ?

Regards
--
Albert SHIH
Observatoire de Paris
France
xmpp: jas@obspm.fr
Heure local/Local time:
Fri 11 Oct 2019 04:27:48 PM CEST





^ permalink  raw  reply  [nested|flat] 2+ messages in thread

* Re: Strange behavior over WAN
  2019-10-11 14:38 Strange behavior over WAN Albert Shih <Albert.Shih@obspm.fr>
@ 2019-10-11 19:04 ` Fernando Hevia <fhevia@gmail.com>
  0 siblings, 0 replies; 2+ messages in thread

From: Fernando Hevia @ 2019-10-11 19:04 UTC (permalink / raw)
  To: Albert Shih <Albert.Shih@obspm.fr>; +Cc: pgsql-admin

El vie., 11 de oct. de 2019 a la(s) 11:38, Albert Shih (Albert.Shih@obspm.fr)
escribió:

> Hi
>
>
> We got a postgresql server with a very small database ( ~few Mo) and do
> a extract with a ruby (sequel) client.
>
> If I do the extract on the same server the speed is correct (10-30 sec)
>
> If I do the extract on the same LAN the speed is correct. (10-30 sec)
>
> If I do the extract from the wan the speed goes from slow to ultra-slow
> (reach the TTL and sometime the connection are close) (1 minutes -> 8
> minutes)
>
> When this happen I try to see if they are some bandwith problem, and they
> don't have any bandwith problem ( ~10-20Mbytes/s 120-180Mbits/s), the size
> of the extraction (with tcpdump) are small (~2Mo).
>
> I also check the fragmentation of the tcp flow, when I'm on the wan they
> are x2 packets so I can understand they are slower than over the LAN but I
> can see how it's possible to go 50-60x slower.
>
> Any idea ? ....or solution ?
>
>
Hi there. Your issue is most probably latency.
This article will give you some pointers on the subject and what you can do
about it (change your data extraction method):
https://www.2ndquadrant.com/en/blog/postgresql-latency-pipelining-batching/

^ permalink  raw  reply  [nested|flat] 2+ messages in thread

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2019-10-11 14:38 Strange behavior over WAN Albert Shih <Albert.Shih@obspm.fr>
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