Re: Throttling Streamming Replication

On Friday, January 25, 2013 at 23:59, Rodrigo Pereira da Silva wrote:

>We are having a problem with our infrastructure provider because the
>network traffic between master and slave server is reaching more than
>30k packages per second(SLA says 20k/second).
>
I note the later post where the infrastructure provider has
determined it is their problem, however you might well benefit
from this as a warning and trim your traffic anyway.

>Is there any way to throttle the streamming replication? I meant, any
>parameter that I set the max number of megabytes sent to standby
>server per second?
>
I am guessing (i.e., no knowledge of your setup) you would
prefer to not have a lot of delay between the master and slave
servers. This is especially so if the slave has to become master
since people mostly want that transition to appear seamless to
the outside world. So increasing time settings may not be
suitable even if it did reduce bandwidth.


It is possible to get serious bandwidth savings without
increasing latency.

ref: <http://permalink.gmane.org/gmane.comp.db.postgresql.general/164874>

If you put each WAL file through pg_clearxlogtail (it zeros out
the unused part of the fixed-length WAL file) then
compress-transmit-decompress the result you will get much better
use of the available bandwidth between master and slave servers.
Specifically you will only be sending information that is
needed, and smaller data chunks are faster data chunks.

Regards
Gavan Schneider



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