Re: external table parallel issue
- From: Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>
- To: exriscer@xxxxxxxxx
- Date: Sat, 15 May 2010 14:02:49 -0700
More data please!
- what DOP?
- what version?
- what is the plan?
Lets start with the data you are looking at, not just your
observation. Otherwise people just guess.
On Sat, May 15, 2010 at 5:52 AM, LS Cheng <exriscer@xxxxxxxxx> wrote:
> I have a query which runs against 64 external tables, the query uses union
> all to return the results.
>
> The query is really slow even with high parallel degree and I noticed that
> it is because in the 64 external tables most of times the last 50 tables
> hasnt got any rows so when the parallel coordinator assigns slaves many
> times the first two slaves reads the 14 tables with most of data and the
> rest reads the empty tables. Due to this even I use parallel the query is
> pretty slow.
--
Regards,
Greg Rahn
http://structureddata.org
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