Re: [Postgres-xc-developers] Node management

[Koichi S. <koi...@gm...>]

Unfortunately, we don't have this at our focus now.    This is
executor/planner improvement, i think.   I hope some of them can be focust
in the next development round.     Anyway, if the planner cannot identify
specific datanodes to go, coordinator has to go to all the datanodes, which
will fail if any one of the datanodes is down.

Up to now, XC development was focused on the feature where all the nodes
are up.    XC architecture allows any transactions to be successful as long
as the failed node is not involved.    I understand that XC behavior has
something to improve in the case where some nodes are gone.

Your input is very valuable and helpful.     We can share this and discuss
how to solve them.

Regards;

----------
Koichi Suzuki


2013/7/11 Pavan Deolasee <pav...@gm...>

> Hello All,
>
> I wonder how do we currently handle node failures in XC setup. I
> understand, we recommend setting up replicated slaves for all the datanodes
> and adjust the coordinator node information in case of fail over, say by
> using ALTER NODE. What I am more curious is about working at a reduced
> availability. Let me give an example:
>
> Say I have a table distributed by HASH on 4 nodes. If one of those nodes
> go down, I would still like to use the table by somehow adjusting the
> metadata at the coordinator. The data stored on the failed node will not be
> accessible, but I should be able to query the data from the remaining
> nodes. So SELECTs should not fail or at the least SELECT with a
> qualification which filters out data from the failed node should not fail.
> Also, INSERT/UPDATE/DELETE should succeed as long as the target node is up
> and running.
>
> I tried to run a few queries to see if this is possible, but could not get
> the desired result. I only had limited success with replicated tables, in a
> sense that I could query the table after dropping the failed node at the
> coordinator. But even that looks fragile.
>
> Are there any action items around this area targeted in the immediate
> roadmap for XC ?
>
> Thanks,
> Pavan
>
>
> --
> Pavan Deolasee
> http://www.linkedin.com/in/pavandeolasee
>
>
> ------------------------------------------------------------------------------
> See everything from the browser to the database with AppDynamics
> Get end-to-end visibility with application monitoring from AppDynamics
> Isolate bottlenecks and diagnose root cause in seconds.
> Start your free trial of AppDynamics Pro today!
> http://pubads.g.doubleclick.net/gampad/clk?id=48808831&iu=/4140/ostg.clktrk
> _______________________________________________
> Postgres-xc-developers mailing list
> Pos...@li...
> https://lists.sourceforge.net/lists/listinfo/postgres-xc-developers
>
>