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From "Matthew Baird" <Matthew.Ba...@motiva.com>
Subject RE: Scrollable Result Sets and Oracle JDBC Performance
Date Fri, 20 Dec 2002 02:06:31 GMT
this has been fixed in CVS. There was some old code that used to cache statements so we always
made them scrollable (bad move), and the other issue was using prefetching requires scrollable
results, so I check that before I set it.

I know it helps performance quite a bit!

regards,
m

-----Original Message-----
From: Matt Mastrangelo [mailto:mmast@ccs.neu.edu]
Sent: Thursday, December 19, 2002 9:58 AM
To: ojb-dev@jakarta.apache.org
Cc: ojb-user@jakarta.apache.org
Subject: Scrollable Result Sets and Oracle JDBC Performance


OJB's hard coded use of scrollable result sets causes a performance issue with Oracle's JDBC
drivers.  The following is a direct excerpt from Oracle's JDBC documentation:

Important: 
Because all rows of any scrollable result set are stored in the client-side cache, a situation
where the result set contains many rows, many columns, or very large columns might cause the
client-side Java virtual machine to fail. Do not specify scrollability for a large result
set. (http://download-west.oracle.com/docs/cd/B10501_01/java.920/a96654/resltset.htm#1008310)

Because of this, the ability to explicitly specify the type of result set used in each query
is important when using OJB with Oracle.  Although this can be achieved by setting the jdbc-level
to 1.0 in the repository.xml, this solution limits to non scrollable result sets only.  In
certain situations, one type of result set may be more appropriate than the other.

Are there any plans to implement such a feature, which would allow the explicit specification
of the result set type?  This would seem to be crucial to OJB's compatibility with Oracle.

Thanks,

Matt

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