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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!

Brrett
________________________________________
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
https://issues.apache.org/jira/browse/DERBY-6022

Hope this helps,
-Rick



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