Re: Weird exception thrown

> I have an application that reads an XML file, parses it and saves its data
> into an Oracle database. The save is actually an insert, if the record
> doesn't exist or an update if the record exists. In order to figure out
> which operation I have to perform, I execute a select, to check whether
the
> record is already in the database. I build the Select SQL statement,
create
> an Oracle Command object with it and then call its Execute Reader method.
> This method returns an OracleDataReader object and for that, all I care to
> check is to see whether it has any records. The OracleDataReader class has
a
> property called "HasRows" that will tell me just that.
> I know what you are thinking: I should ask this question on a different
> forum, like one Oracle hosts for their ODP.NET development, but bare with
me
> for a second.
> After running for 2-3 days continuously, my application starts throwing
this
> weird exception where it says that "Memory could not be allocated". I
> managed to trace the raise of the exception to the invocation of the
> "HasRows" property for the OracleDataReader object. The problem is that,
> looking at the documentation, that property is not raising any exceptions,
> so what the heck is going on.
> To keep things under control, I even tried to kick in the garbage
collection
> (GC.Collect()) myself, every now and then. Now the exception takes longer
to
> be triggered, but eventually it is triggered.
> Can anyone give me some ideas as to what else to try and figure out what
the
> problem is? The XML files are not really big, averaging around 100 kB
each.
> When the exception is triggered, I look ion the task manager and Physical
> Memory usage is nowhere near the top.
> Any suggestion will be highly appreciated.

	Oracle's ODP.NET is actually a wrapper around their java CLI code,
so it has unmanaged elements everywhere, even OracleParameter objects have
unmanaged elements. 

	This means that you have to call Dispose() on 
- OracleParameter
- OracleDataReader
- OracleCommand
- OracleConnection

	It's not enough to call Dispose on OracleConnection or
OracleCommand, nor is it enough to call Close on OracleDataReader. 

	If you don't do this, you'll get subtle memory leaks which
eventually will bring the system down. 

	As you're using Oracle, you can do without the select however, use
the MERGE statement:
http://www.fast-track.cc/10g_166.htm
	If you're on 9i you can use an upsert:
http://www.praetoriate.com/oracle_tips_upserts.htm
	If you're on an even older dinosaur (poor sod ;)), you're out of
luck and will have to use the select separately. 

	Good luck.

		FB


------------------------------------------------------------------------
Lead developer of LLBLGen Pro, the productive O/R mapper for .NET
LLBLGen Pro website: http://www.llblgen.com
My .NET blog: http://weblogs.asp.net/fbouma
Microsoft MVP (C#)
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