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.
