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From Mirko <>
Subject Re: GenericJDBCDataModel problem (getItems, getUsers)
Date Thu, 05 Nov 2009 16:43:32 GMT

> Yes I would encourage you to switch, since a lot has improved, but yes
> the Strings-longs issue is the biggest one. It does enable quite a bit
> of performance improvement.

Ok, I switched to v0.3 and also use a MySQL DB to store preferences  
now. It was easy to implement with MySQL, although performance is  
still bad, but I didn't tweak MySQL server variables yet and also work  
with small JVM memory on my notebook.

> One possibility is that there are no results because
> the SQL isn't quite querying how you want it, or being executed as you
> think it is, and is returning no results. For example if you don't
> have the order of the placeholders right (the '?') things wouldn't
> work.

Well, the queries for getUsers and getItems have no parameters. Also,  
wrong number of parameters do throw exceptions.
> This is why I wonder if you can look at the log statements from the
> library (at debug level) which show the SQL statements being executed.
> Or simply attach a debugger and find out that way.

Jep, this is what I did already. I looked at the logs from the library  
at debug level. From there, I copy-pasted the SQL statements and  
checked their results. And as I said, no exceptions are logged. But  
nevermind, I switched to v0.3 and MySQL anyway, so there's no use to  
get v0.1 working anymore.

Maybe I will go back to implementing a DataModel for my RDF store with  
the current code version later. I like the idea not to need a special  
table for preferences, but to query preferences from RDF directly.  
However it makes not much sense anymore when needing LongIDs. I would  
have to translate-and-copy the data, which must use StringIDs,  
anyway). I will think about that...


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