[pgpool-general: 4708] Re: Pgpool and postgis

Muhammad Usama m.usama at gmail.com
Thu May 26 21:44:09 JST 2016

On Thu, May 26, 2016 at 2:29 PM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> > Hi,
> >
> > I'm evaluating a pgpool cluster with 2 nodes as a substitute for the
> single
> > postgresql instance we are using now.
> >
> >>From an application perspective, my main concern is postgis. We are
> > extensively using postgis in our applications. As I understood pgpool
> will
> > transparently handle any pgsql write instruction like insert or update,
> but
> > how are statements like AddGeometryColumn handled? Do I need to put every
> > "write" statement in the black_function_list?
> Basically yes. Recently Usama eliminated the space limitation of the
> memory area for black_function_list and you can register as many as
> function names you like.
> Usama, do you have any suggestion for this?

Not really. Basically black_function_list is the best way to make sure that
the statement with writing function lands on the master node. Alternatively
query can be prefixed with /*NO LOAD BALANCE*/  comments, but that will
require the changes on the application side.
Another thing to note here is black_function_list and whie_function_list
also support regular expression, So if there is a specific prefix that all
writing functions have than instead of putting the name of each and every
function in the list a generic regular expression can also be used.

Muhammad Usama

> > As a side note, we have been provided with 2 db nodes with the same size
> as
> > our singel instance, but the two watchdog machines are 2 cores instances
> > with only 1G or ram, is this enough to run the watchdog smoothly? We have
> > around 1K IOPS.
> Pgpool (and watchdog) does not consume too much CPU and memory and
> usually the resource you are given should be enough to handle the
> load. I think network device performance is rather important, since
> pgpool needs to handle lots of network traffics.
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
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