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From Prasenjit Sarkar <psar...@almaden.ibm.com>
Subject Re: Derby Performance Problem
Date Tue, 11 Apr 2006 17:05:50 GMT
Looks like the problem is worse in the snapshot version - 6.5 minutes in
Derby vs 2 s in DB2. I'll post a defect in Jira -- I'll probably attach the
database and the query in question...

Prasenjit Sarkar
Research Staff Member
Master Inventor
Storage Systems
IBM Almaden Research

             Rajesh Kartha                                                 
             om>                                                        To 
                                       Derby Discussion                    
             04/10/2006 06:41          <derby-user@db.apache.org>          
             PM                                                         cc 
             Please respond to         Re: Derby Performance Problem       


I am wondering if it is related to the issue -

If you have an older version (than, is it possible to re-run
you scenario
using  the newer snapshot jars posted at:

Please do post your findings.


Prasenjit Sarkar wrote:

>We are porting a commercial application from DB2 to Derby and have run
>a performance issue. Our application has a very complex data model and
>four levels of views for some reports. We are facing a performance problem
>in joining views at the second level.
>To illustrate an example, VIEW_L2_1 and VIEW_L2_2 are two views at the
>second level. Both VIEW_L2_1 and VIEW_L2_2 compute very fast (<1s). For
>experiment in question, the cardinality of VIEW_L2_1 and VIEW_L2_2 is only
>300 and 10 respectively - each row in VIEW_L2_1 and VIEW_L2_2 has less
>128 bytes of data. So, we are not talking large datasets here. Both views
>are dependent on some common views at the first level.
>The issue is this: a join of VIEW_L2_1 and VIEW_L2_2 on a simple equality
>condition (on a column each from one view) takes 2-3 minutes on Derby,
>while the equivalent query in DB2 computes very fast (<1s). It looks like
>that the Derby query engine is CPU-bound for the most part during the
>The statistics obtained do not shed much light on this issue.
>I'm fairly new to Derby and would like some direction on how to proceed.
>Prasenjit Sarkar
>Research Staff Member
>Master Inventor
>Storage Systems
>IBM Almaden Research

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