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From Kathey Marsden <kmarsdende...@sbcglobal.net>
Subject Re: Disussion surrounding holding off metadata changes until certain issues resolved
Date Sun, 09 Apr 2006 16:08:33 GMT
Dag H. Wanvik wrote:

>>Old client, new server scenario: In this case, the downgrade of the
>>result set happens on the client, so applications would not be able
>>to use SUR. Only the new client lifts the restriction.
>>
>>Due to the bug in the 10.1 client code for
>>supportsResultSetConcurrency (DERBY-965), the client would still get
>>a "false" on this query, which is correct. Note that this is be
>>accident rather than by design! Derby has a weakness here in that
>>metadata queries are answered by the server without regard to the
>>client's version (capabilities).
>>    
>>
Thank you so much for calling out this potential compatibility issue in
this thread.  DERBY-775 was not on my compatibility radar.

I tried  the repro for DERBY-965 with JCC and the trunk server and see
that JCC returns false these values for supportsResultSetConcurrency, so
I think that we are ok for JCC too.  Is that correct?

com.ibm.db2.jcc.DB2Driver:
SupportsResultSetConcurrency: TYPE_FORWARD_ONLY,CONCUR_READ_ONLY: false
SupportsResultSetConcurrency: TYPE_FORWARD_ONLY,CONCUR_UPDATABLE: false
SupportsResultSetConcurrency: TYPE_SCROLL_INSENSITIVE,CONCUR_READ_ONLY:
false
SupportsResultSetConcurrency: TYPE_SCROLL_INSENSITIVE,CONCUR_UPDATABLE:
false
SupportsResultSetConcurrency: TYPE_SCROLL_SENSITIVE,CONCUR_READ_ONLY: false
SupportsResultSetConcurrency: TYPE_SCROLL_SENSITIVE,CONCUR_UPDATABLE: false
Apache Derby Network Server - 10.2.0.0 alpha shutdown at 2006-04-09
15:38:51.040 GMT


>Generally, it seems results of such metadata calls should potentially
>be "negotiated down" if the client is older and cannot support the new
>feature.. I am not sure of the machinery of NetDatabaseMetaData can be
>used as is for this purpose...(i.e. the serverSupport<FeatureX>
>methods). Or?
>
>  
>
Right, I think there is still a hole here in terms of metadata handling
and how to negotiate down.  I am guessing that will become incumbent on
someone who finds that they need  that negotiation for some  new
feature.    It looks like you are "off the hook" this time  because of
DERBY-965.




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