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Re: FDW wrapper for clustered app management - Mailing list pgsql-general

From Jerome Wagner
Subject Re: FDW wrapper for clustered app management
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Msg-id CA+=V_fNbhq8PzgQUc7C+Hk6XyiGkyRS5Ou9ea3MaFo=0z0W=0Q@mail.gmail.com
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In response to Re: FDW wrapper for clustered app management  (John R Pierce <pierce@hogranch.com>)
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Hello John,
Thanks for your answer. I am also considering a publish/subscribe MQ based solution (and this may be indeed needed for queuing RPCs).

the data I would like to access R/W is more like
 - configuration data
 - states of different state machines
 - cache values for some keys (reading, invalidating)

so you could in a sense say that they are table oriented.

I agree that this becomes 'tangential' with write access.
a request like "UPDATE server.service SET start_requested = true WHERE name = 'myService' and started = false" seems weird but it could probably work.

Thanks,
Jerome

On Fri, Oct 17, 2014 at 11:57 AM, John R Pierce <pierce@hogranch.com> wrote:
On 10/17/2014 2:35 AM, Jerome Wagner wrote:
Hello,

I am considering (postgres 9.3+) the idea of opening a R/W access into a clustered application by creating one fdw server from a central database to each server a cluster.

That would imply opening a port on each server inside the application, listening for incoming connections from the database and this way all the servers would become visible with R/W access.

Is that a sound idea or does it look horrible ? Would it be reasonable to connect in this way to a cluster of 1, 10, 100, 1000 or more servers ?

is there an existing xxxx_fdw wrapper that would look like a good candidate for such a direct access inside an application ? Then I would have to implement the protocol corresponding to this xxxx_fdw inside my application.


is the application running on these 10, 100, 1000 nodes something resembling a table oriented relational database?

I would suggest instead you look at using a MQ style message queueing system, with publish-subscribe semantics for your distributed remote procedure calls. and not from within a database, rather, from your central control application to your distributed application workers...




--
john r pierce                                      37N 122W
somewhere on the middle of the left coast



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