RE: Optimizer question after upgrade
- From: "Michael McMullen" <ganstadba@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 20 Mar 2009 07:57:54 -0400
I'll try to find the article (I think it's an oracle white paper) where they
went through an 9i to 10g upgrade. It started out being 10-20% slower for a
key batch job and then by the time they were done it was 10% faster.
I believe the key steps were.
1. Take out any hidden parameters ie start with base 10g pfile, nothing from
9i
2. Take out hints from your sql. Really you want to start out cold, nothing
left from 9i
3. Have system statistics -- I myself hate system statistics. You get a
brand new box, how do you set them to mimic your full prod without running
your processes. It seems like a swag to me. They vary depending on the
workload of the system. I like to bring over one business area at a time to
a new box, get things running smoothly and then the next. But if I run
system stats after I bring a bunch of new biz areas over, they can change
which could change the execution plans of the first biz area I brought over.
I find it very much a chicken/egg sort of thing.
4. Be really depressed, as the article was long and involved a lot of steps
and if it was a live production system you would have been screwed.
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