Re: external table parallel issue

  • From: Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>
  • To: LS Cheng <exriscer@xxxxxxxxx>
  • Date: Sun, 16 May 2010 18:32:22 -0700

First off - why not just make a single external table that contains
all the files of the other 64?  E.g if you have 64 external tables
with 1 file each, make a single, additional, external table with 64
files.  This would seem to eliminate the need for a 64 branch union
(which seems like bad design to me).
Second - does the issue (which I'm unclear on exactly what it is)
reproduce if you use heap tables?  E.g make N heap tables as select *
from external_table and try your 64 branch union.

If your concern is why some PX servers dont seem to be getting work
when accessing the external table - does this reproduce with a simple
select count(*) from the external table as well?

On Sun, May 16, 2010 at 9:26 AM, LS Cheng <exriscer@xxxxxxxxx> wrote:
> The size varies from a few MB to a couple hundreds of MB.
> With 1 external table the query is pretty fast, we have other process which
> run against only a single external tables larger than the problematic one
> and the timing is much better.
> The problem with this I am showing is that it is formed by many external
> tables and to simply the query we created several union all views on top of
> these external tables. I will test without views and see what happens.

Greg Rahn

Other related posts: