Re: PDML and PQ tunning
- From: "Radoulov, Dimitre" <cichomitiko@xxxxxxxxx>
- To: Herring Dave - dherri <Dave.Herring@xxxxxxxxxx>
- Date: Wed, 23 Nov 2011 16:52:06 +0100
Hi Dave,
thanks again for your valuable input!
Comments in-line.
On 23/11/2011 15:45, Herring Dave - dherri wrote:
> Increasing the right memory parameters may be your best bet, as it seems
> you've already planned to do so. With parallel operations, you typically
> need more memory as each PX slave needs memory. Parallel operations work
> best when you can throw resources at it, pretty much a brute force method.
> It'd be interesting to see what the PGA advisor says in a statspack report,
> as in how much of an increase would help, if any.
Requested 2 weeks ago, I'm still waiting for the statspack reports ...
> Sqlplus ARRAYSIZE usually doesn't help much past a value of 300, at least in
> my testing. And that's only for dealing with results returned to your
> session. In the production setting, are they really going to be running this
> query with the expectation of returning 400 MB or so of data (500,000+ rows)
> to their PC?
No, the real statements do insert ... select.
In production I can only test the select part and not the complete
insert ... select ... statement.
> If not then try to rewrite the query in tests to return no rows yet leave
> the plan the same. For example, make the main query just an inline view with
> the outer-query performing some aggregation so only a few rows are returned.
> Obviously you'll need to run a number of EXPLAIN PLAN FOR ... attempts to
> make sure the plans haven't changed, as Oracle may optimize the query because
> of the aggregation.
I'll try to simulate more closely these insert ... select statements.
Best regards
Dimitre
--
//www.freelists.org/webpage/oracle-l
Other related posts:
