RE: Parallel query on when it's not supposed to be (?)
- From: "Bobak, Mark" <Mark.Bobak@xxxxxxxxxxxxxxx>
- To: <gogala@xxxxxxxxxxxxx>, <mrichard@xxxxxxxxxxxxxxxxx>, "oracle-l" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 15 Sep 2004 01:43:20 -0400
Gee, I guess I should have read Mladen's message before posting!
He already pretty much covered it!
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx on behalf of Mladen Gogala
Sent: Wed 9/15/2004 12:05 AM
To: mrichard@xxxxxxxxxxxxxxxxx; oracle-l
Cc:=09
Subject: Re: Parallel query on when it's not supposed to be (?)
On 09/14/2004 10:03:10 PM, Mark Richard wrote:
>=20
>=20
>=20
>=20
> I just wanted to pose a question to anyone on the list (particular the =
wait
> event guru's like Cary)...
Event guru? That's what Cary is? Hmmm, not exactly the expression
that I'd use.
>=20
> Eliminating parallel query because you are seeing waits for it sounds =
to me
> a little like tuning the BCHR. I can't help but wonder if waiting for =
a
> parallel query is still the quickest way to get things done? Would =
killing
> the parallel query effectively move the waits to another category =
without
> achieving any real gain?
If the instance is OLTP with several hundreds of concurrent users, you =
definitely
don't want PQ utilized by users, on regular basis, because it would =
quickly=20
drain your machine resources. If a full table scan somehow makes it into =
production,
and it happens even to the best of us, then you want to minimize the =
damage and
not resolve it by devoting enormous resources to it, thus starving =
everybody=20
else of CPU power. PQ is not a magic potion thad druid Getafix used to =
cook
(I apologize to my American friends who have never heard of Asterix and =
Obelix)
to increase power of the tiny Gaul warrior, PQ is a tool that has its =
place,
primarily in the batch and DW systems. Enabling PQ on a busy OLTP =
instance is
something that can be compared to another French comic, namely Gaston. =
There are
many French speaking people on this list, they may explain to you =
everything
about Gaston Lagaffe.=20
--=20
Mladen Gogala
Oracle DBA
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