Date: Sun, 20 Nov 2005 10:28:57 +1300
From: Mark Kirkwood <markir@paradise.net.nz>
Subject: Re: Hardware/OS recommendations for large databases (
In-reply-to: <BFA3ABF0.14124%llonergan@greenplum.com>
To: Luke Lonergan <llonergan@greenplum.com>
Cc: Dave Cramer <pg@fastcrypt.com>, Greg Stark <gsstark@mit.edu>,
	Joshua Marsh <icub3d@gmail.com>, pgsql-performance@postgresql.org
Message-id: <437F9919.20305@paradise.net.nz>
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Luke Lonergan wrote:
> Mark,
> 
> On 11/18/05 3:46 PM, "Mark Kirkwood" <markir@paradise.net.nz> wrote:
>  
> 
>>If you alter this to involve more complex joins (e.g 4. way star) and
>>(maybe add a small number of concurrent executors too) - is it still the
>>case?
> 
> 
> 4-way star, same result, that's part of my point.  With Bizgres MPP, the
> 4-way star uses 4 concurrent scanners, though not all are active all the
> time.  And that's per segment instance - we normally use one segment
> instance per CPU, so our concurrency is NCPUs plus some.
>

Luke - I don't think I was clear enough about what I was asking, sorry.

I added the more "complex joins" comment because:

- I am happy that seqscan is cpu bound after ~110M/s (It's cpu bound on 
my old P3 system even earlier than that....)
- I am curious if the *other* access methods (indexscan, nested loop, 
hash, merge, bitmap) also suffer then same fate.

I'm guessing from your comment that you have tested this too, but I 
think its worth clarifying!

With respect to Bizgres MPP, scan parallelism is a great addition... 
very nice! (BTW - is that in 0.8, or are we talking a new product variant?)

regards

Mark