db-derby-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From david myers <david.myers.scibearsp...@gmail.com>
Subject Re: Derby Key Words
Date Tue, 04 Sep 2012 20:55:03 GMT
On 31/08/12 15:00, Rick Hillegas wrote:
> 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
Hello again all.

Things are progressing.... sort of ;)

I've had success in pointing Eclipse to the source code that I have 
built. I have had a nice look around for the file that I am interested 
in, which from the previously mentioned JIRA issues etc suggest a file 
called sqlgrammar.jj
only problem is I can't find it!
This file holds the 2 methods, that I am interested in.
It seems to me that the data must already be locked away somewhere in 
derby, but I haven't yet found where. I haven't even found a 
databasemetadata.java file... yet ?

I guess I'm missing something somewhere...


View raw message