db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Larry Meadors <larry.mead...@gmail.com>
Subject Re: OOM with millions of weakly-referenced Derby objects
Date Tue, 17 Nov 2009 18:59:14 GMT
The expected behavior is really dependent upon the underlying JDBC driver.

Using the maxRows parameter is a last resort option, IMO.

Limit the results with the SQL if at all possible, here's an example:

http://old.nabble.com/top-N-reporting-with-derby-td17221545.html

Larry


On Tue, Nov 17, 2009 at 11:42 AM, Eric Floehr <Eric.Floehr@3x.com> wrote:
> All,
>
>
>
> I have a Derby table with up to a million rows.  Some large subset of those
> rows may be returned by a SELECT query.
>
>
>
> I am using IBATIS quertyForList with the embedded Derby driver.  I am using
> the version which has a maxRows parameter.  I call that method and receive
> back the proper “maxRows” java.sql.ResultSet objects.  For example, the
> select would match 100,000 rows, but I only get the first 200.  That all
> works fine.
>
>
>
> However, I am getting OOM’s when the select would match nearly a million
> rows and after profiling with JProfiler the culprit seems to be millions of
> weakly referenced org.apache.derby.iapi.types.SQL objects (SQLLongInt, for
> example) that appear to be created far faster than they can be GC’ed.  This
> particular performance test run would return a million records, of which I
> am only wanting to retrieve the first 200.
>
>
>
> My questions are:
>
> 1.       Is this expected behavior?
>
> 2.       Is IBATIS properly using a cursor, or what is the right way to
> limit the number of Derby objects created (the ResultSet count is correct)
>
> 3.       Are there Derby or IBATIS parameters that can be employed to
> correct this behavior?
>
>
>
> Derby version is 10.5.3, IBATIS version is 2.3.4.726, and Java version is
> 1.6.  I have cross-posted to both the Derby and IBATIS lists since I don’t
> know where the root problem resides.
>
>
>
> Thanks so much for your help!
>
>
>
> Best Regards,
>
> Eric
>
>

Mime
View raw message