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From Daniel John Debrunner <...@apache.org>
Subject Re: Collation implementation WAS Re: Should COLLATION attribute related code go in BasicDatabase?
Date Thu, 15 Mar 2007 18:58:21 GMT
Mike Matrigali wrote:
> 
> 
> Mike Matrigali wrote:
>>
>>
>> Daniel John Debrunner wrote:
>>
>>> Mike Matrigali wrote:
>>>
>>>> I think I am missing/not understanding your direction.
>>>>
>>>> are there still 4 new types?
>>>
>>>
>>>
>>> No, collation becomes an attribute of the existing character types 
>>> just like length and nullability are.
> What is CollatorSQLChar in your proposal then?

Same as in Mamta's current code.

CollatorSQLChar is a DataValueDescriptor, these are holders for values 
of a type, they are not a type themselves. I think that's where the 
confusion is coming in.

A type in Derby is composed of much more. The type definition of a 
column is described by a DataTypeDescriptor, it is this class that would 
  hold extra information (an int) to describe the collation type. Also 
some changes for classes involved in type creation at compile time will 
be needed, CharTypeCompiler at least.

A writeup of the roles of the type classes is in the package.html for 
the types package.

http://db.apache.org/derby/javadoc/engine/org/apache/derby/iapi/types/package-summary.html#package_description

So there would be four new classes that implement DataValueDescriptor, 
for the Collator based collation of the four existing character types, 
as Mamta has implicitly proposed. But there would not be four new 
internal types and all the overhead it entails.

Dan.


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