Re: [Postgres-xc-developers] ExecRemoteQuery

[Pavan D. <pav...@gm...>]

On Mon, Aug 12, 2013 at 9:54 AM, Ashutosh Bapat <
ash...@en...> wrote:

>
> Welcome to the mess ;) and enjoy junk food.
>
> Sometime back, I have changed ExecRemoteQuery to be called in the same
> fashion as other Scan nodes. So, you will see ExecRemoteQuery calling
> ExecScan with RemoteQueryNext as the iterator. So, I assume your comment
> pertains to RemoteQueryNext and its minions and not ExecRemoteQuery per say!
>
> This code needs a lot of rework, removing duplications, using proper way
> of materialisation, central response handler and error handler etc. If we
> clean up this code, some improvements in planner (like using MergeAppend
> plan) for Sort, will be possible. Regarding materialisation, the code uses
> a linked list for materialising the rows from datanodes (in case the same
> connection needs to be given to other remote query node), which must be
> eating a lot of performance. Instead we should be using some kind of
> tuplestore there. We actually use tuplestore (as well) in the RemoteQuery
> node; the same method can be used.
>
>
If we at all want to rework that, IMHO we should just use ForeignScan with
appropriate enhancements to the node and/or addition of a new node to
effectively combine results from multiple ForeignScan nodes.

Thanks,
Pavan

-- 
Pavan Deolasee
http://www.linkedin.com/in/pavandeolasee