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From Daniel John Debrunner <...@debrunners.com>
Subject Re: Question about softupgrade mode ..
Date Tue, 26 Apr 2005 19:25:56 GMT
TomohitoNakayama wrote:
> Hello
> I have question about softupgrade mode...
> Is it allowed for implementation in parts such as SQL layer of engine
> to make conditional processing according to version in order to realize
> softupgrade mode ?

Typically the soft-upgrade check is made to disallow new features, e.g.
at compile time a check would be made to disallow the BY DEFAULT option
of the GENERATED syntax, unless the database had been upgraded to 10.1.
See the checkVersion() call in CreateAliasNode.java

It is possible to also make the check and change the behaviour, I assume
you mean storing the generated column information for the ALWAYS option
in a different way in 10.1 and beyond, compared to 10.0. If you choose
that direction then you may need to have hard-upgrade code that modifies
the existing on-disk generated column information.

> I'm working on DERBY-167 and,
> rule of nullOrNot about DefaultInfo and attiriubutes of DefaultInfo
> would be changed in this issue.
> Because updating those information on database affects working of
> previous version,
> conditional processing to work correctty on previous database would be
> unavoidable to realize softupgrade mode...

It would be useful if you could explain your planned changes in how
generated column information will be stored on disk.


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