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From "Stephan van Loendersloot (LIST)" <step...@republika.nl>
Subject Re: Merging two Derby databases, update database structure to old one
Date Tue, 14 Oct 2008 23:00:33 GMT
Juho Tykkälä wrote:
> Stephan van Loendersloot (LIST) kirjoitti:
>> Juho Tykkälä wrote:
>>> Why I ask is: If I'm going to add more features to my software,
>>> which uses Derby database, and these features need database
>>> structural changes, how can I update my customer's old software
>>> versions without touching the data inside their databases. Just
>>> need to add few columns more and don't want to clear data inside 
>>> database.
>> Hi Juho,
>> You can use the same statements that you applied on your development 
>> database to update your customers' databases. Just be aware of common 
>> pitfalls when altering databases on productions systems, though.
> Hi Stephan,
> Yes, I know alter table.
> What I meant was: Is this possible by only moving and merging files
> located at database/seg0/ directory? If it is, it would be much more
> easier because I could update database changes among
> other files using just "plain installation script" or other installer.
Hi Juho,

Sorry, but that's not possible. Even if it were, then the database would 
have to be made aware of changes in the filesystem, or perform some sort 
of scanning to be able to recognize and integrate changes.

Besides, files that are in use by the database may be locked by the 
operating system while being read from or written to..

Guess you'll have to stick to regular updates.



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