El vie., 11 de oct. de 2019 a la(s) 11:38, Albert Shih (Albert.Shih@xxxxxxxx) 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/
