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From Daniel John Debrunner <...@apache.org>
Subject Re: Creating User Types in Derby
Date Thu, 15 Nov 2007 00:54:35 GMT
Rick Hillegas wrote:
> Hi Samuel,
> 
> I agree with Dag that this issue is a little complicated and you may 
> want to tackle something smaller first just to get familiar with the 
> Derby codeline. The objects stored in system tables, which Dag 
> mentioned, are a special kind of user defined type with a highly 
> optimized storage representation. A good place to start is to grep the 
> codeline for UserDefinedType. This will introduce you to a lot of 
> compiler support for user types.

I think that the storage support for Java serializable types is pretty 
much complete, the big part of this project will be adding the DDL (SQL 
standard part 13) and the testing.

The system columns are only special in that they implement an internal 
interface for writing themselves to disk. If they only implemented 
java.io.Serializable or java.io.Externalizable then they would be 
written by the store using those interfaces. I believe for the rest of 
the code they are just handled as a generic Java type.

Dan.



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