[Postgres-xc-developers] Node management

[Pavan D. <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