[Fwd: Re: LSARC/2007/299 Berkeley_Database_4.5.20 - fast track restarted]

[Danek Duvall]

On Fri, Dec 14, 2007 at 02:01:56PM -0800, Karen Langford wrote:

> We haven't discovered any incompatibilities nor does Oracle publish any
> incompatibilities between the two versions. Removing 4.2 from the release
> and only delivering 4.5 creates a risk for product consumers. In the past
> we've had consumers express concern about breakage if we replaced the
> library,
> that said, if we did replace the library they'd have to do a database 
> upgrade
> (which is done with a tool provided). So while there isn't any true library 
> incompatibilities there are necessary steps for an application using
> an old library to upgrade to a new one. 
> Note when we did the ARC case for 4.2 we presented that multiple libraries 
> were desired and it was agreed that they were indeed necessary.
> For this reason and on the advice of LSARC we reengineered the build 
> environment so the libraries would follow Sun ABI guidelines,ie so.1, so.2 
> and so.3.

Okay.

I'm extremely uncomfortable with having multiple copies of the library (any
library, really) on the system without at least some very strong guidelines
(rules, for Sun projects) on how to navigate the problems inherent in the
situation.  Without guidance, it's untenable, and leads us into DLL hell,
just like Windows, and just like Linux.

With proper backwards compatibility, we don't have to go in that direction
at all, and if there is no incompatibility here as you say, then there's no
need for multiple copies.  Just because the ARC said you could do that if
you had to doesn't mean you should if you can avoid it.  As E7 in the
Libraries Best Practice states (and which you claim to conform to),
changing the major version of a library should be an extremely rare event,
needed only when there are incompatible changes.

Are your customers' concerns about breakage founded?

What are the "necessary steps" customers would need to do on upgrade?  Are
all database files subject to explicit upgrade procedures?  What would it
take to make any such upgrade steps hidden from the user?

Danek