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From Kathey Marsden <kmarsdende...@sbcglobal.net>
Subject Re: [jira] Updated: (DERBY-1107) For existing databases JDBC metadata queries do not get updated properly between maintenance versions.
Date Thu, 30 Mar 2006 00:42:46 GMT
Knut Anders Hatlen wrote:

>I'll summarize my understanding of these two issues 
[snip very good explanation]

>As you suggested, the client could invoke the SQL directly. This would
>however cause some problems:
>  - if there is a bug in a metadata query, it is not enough to upgrade
>    the server, you would also have to upgrade all the clients.
>  - if the server changes the name of a system table or a column in a
>    system table, old clients will be broken.

Another problem is that the metadata queries currently use
non-supported  syntax.  Changing these to use supported syntax, such as 
Mamta did when adding optimizer directives would mean that the old
non-supported syntax would have to stay in the server.

One more thing not mentioned here was that  Satheesh for 1120/1124  
added some version dependent metadata queries, which were necessary for
soft upgrade because with the full v10.2  upgrade,   system columns
needed to be accessed for the metadata queries that  were not available
on soft upgrade.  That seemed like a reasonable approach to soft upgrade.

Once all the infrastructure gets firmed up,  it would be good to have
some information on the Wiki about how  maintain metadata queries.   It
is good to see it getting addressed.


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