[netcdf-java] Persisting a NetcdfDatasetCache

[Nick Bower]

I'd also keep in mind that ObjectOutputStream's style of 
storing/retrieving instance attributes then re-attaching the class 
definition could be sufficient.  Databases won't have the performance of 
a lean object cache.

Nils Hoffmann wrote:
> Hi Jon and also to the list,
> Jon Blower wrote:
>   
>> Hi Nick and John (and list),
>>
>> I was about to write pretty much exactly what Nick just wrote - the
>> serialization would be for short-term storage so I don't think there's
>> a problem there (although I guess some people might try to misuse the
>> serialization capability if it were provided).
>>
>> My _guess_ is that there is no need to keep open file handles and the
>> overhead of opening a NetcdfDataset is mostly in the reading of the
>> metadata into the relevant structures (Attributes, Axes etc),
>> particularly if the dataset is an aggregation (actually it was
>> aggregations that I had in mind when I suggested the persistent store
>> in the first place).  However, some testing would be needed of course
>> - I don't really know.
>>
>> Maybe the metadata could be stored in some other way than
>> serialization. We have done some analogous experiments with trying to
>> use a relational database to store metadata but the problem is that
>> the database gets complicated when you start dealing with projections
>> and the like.  Object-relational mapping could help to manage the
>> complexity but this won't be trivial to code (e.g. could use Hibernate
>> over an embedded database like H2).
>>     
>
> Maybe instead of going through the hassle of setting up an OR mapping,
> you might want to have a look at http://www.db4o.com/, which is an 
> object database also for Java. It does not require class annotations
> or xml descriptions of mappings so it is rather quick to set up, 
> although I must admit that I haven't tested it for performance against
> any other solution, yet. It also allows the database to be local, e.g. 
> in a file and even allows for updates of an object's interface to some 
> degree.
>
>   


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