I'll try the patch and let you know the results...
Prasenjit Sarkar
Research Staff Member
Master Inventor
Storage Systems
IBM Almaden Research
Rajesh Kartha
<[EMAIL PROTECTED]
om> To
Derby Discussion
04/10/2006 06:41 <derby-user@db.apache.org>
PM cc
Subject
Please respond to Re: Derby Performance Problem
"Derby
Discussion"
<[EMAIL PROTECTED]
ache.org>
Hi,
I am wondering if it is related to the issue -
http://issues.apache.org/jira/browse/DERBY-649
If you have an older version (than 10.1.2.3), is it possible to re-run
you scenario
using the newer snapshot jars posted at:
http://db.apache.org/derby/derby_downloads.html#Snapshot+Jars
Please do post your findings.
Regards,
Rajesh
Prasenjit Sarkar wrote:
>Hi,
>
>We are porting a commercial application from DB2 to Derby and have run
into
>a performance issue. Our application has a very complex data model and
uses
>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
the
>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
than
>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
time.
>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.
>
>Thanks,
>
>Prasenjit Sarkar
>Research Staff Member
>Master Inventor
>Storage Systems
>IBM Almaden Research
>
>
>
>
