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From Rick Hillegas <rick.hille...@oracle.com>
Subject Re: Derby Key Words
Date Fri, 31 Aug 2012 13:00:38 GMT
On 8/30/12 2:56 PM, David Myers wrote:
> ...
> I think your solution of a table function should work well enough.
> > From the few table functions I have used, I notice that I was also
> able to get the same info from a join of 2 system tables. Is this how
> they generally work (I call the function and an SQL command runs in
> the background)?
Hi David,

What you just described sounds more like a view than a table function to 
me. Table functions are useful for examining data that comes from 
external databases or from non-relational sources. Turning a list into a 
table sounds like a good use of table functions to me.
> Also would it not make some sense to have a method
> within the databaseMetaData object thqt would return either the list
> of values (after calling the new function) or take a string argument
> and return true (the argument is equivalent to a key word) or false.
>
This is an interesting approach and might be cheaper to implement. I 
think we would only need to add the new method to Derby's embedded 
implementation of DatabaseMetaData. We would need to make sure that the 
new method had a name which the JDBC expert group would never want to 
use. The advantages of a table function (can be used in queries, can be 
used across the network by JDBC client apps) could be had by wrapping 
the Derby DatabaseMetaData in something like the DBMDWrapper class 
attached to https://issues.apache.org/jira/browse/DERBY-3973.

Thanks,
-Rick

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