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From "Bergquist, Brett" <BBergqu...@canoga.com>
Subject RE: Why is the optimizer choosing such a bad path
Date Mon, 01 Apr 2013 13:55:35 GMT
I will be looking at this later in the week as of course my real work has interrupted :)  
Thanks for all of the valuable input!

From: Rick Hillegas [rick.hillegas@oracle.com]
Sent: Friday, March 29, 2013 2:10 PM
To: derby-dev@db.apache.org
Subject: Re: Why is the optimizer choosing such a bad path

On 3/29/13 9:30 AM, Mike Matrigali wrote:
> On 3/29/2013 5:28 AM, Bergquist, Brett wrote:
>> Mike I have a reproducible case but the database is 132GB so it is
>> not practical.   I am willing to dig in and try to help debug this.
>> On the issue that was pointed to, Mamta seemed to have used a debug
>> procedure that would print out more information on why the optimizer
>> is choosing what it does.   This might be useful in this case as well.
>> So if someone can point me in the right area of the code to start
>> looking and adding some debug that would be helpful.  I have done
>> some fixes for Derby in the past so I am able to build and debug Derby.
> That's great.  I am out of my depth debugging optimizer problems,
> hopefully rick and/or mamta can help with that tool they were working
> on.  I think rick did some work to make it easier to turn on/off using
> optional tools.
The simpler api to optimizer tracing is part of the 10.10.1 release
candidate which we're testing now. Instructions on how to use it can be
found in my 2013-03-14 comment on

Hope this helps,

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