[Zope3-dev] Tossing Data.fs considered harmful

[Steve Alexander]

Tres Seaver wrote:
> I would like to ask for consensus among the Zope 3 development community
> that we stop requiring people to discard existing databases without
> recourse.  In particular, this week has seen two changes which caused
> working sites to break, and which offered no possibility of saving any
> data or TTW software (actually, the "service renaming" change left the
> database readable, but applications broke;  the "opaque pickles" branch
> makes the database unreadable).
> 
> Continuing the current practice is an active disincentive for people to
> begin building applications and sites with Zope3.  Such "higher-level"
> development is going to be increasingly important as we go forward:  it
> provides important feedback about the usefulness and usability of the
> infrastructure.  Having working, interesting applications be available
> for the Zope3 platform seems essential before we can event contemplate a
> release;  such applications won't be written prior to the release if we
> frustrate their authors into abandoning Zope3 due to repeated data loss.
> 
> I would therefore propose that any future changes which have such an
> inmpact remain unmerged until they include a conversion script or other
> mechanism to provide forward compatibility.

I generally agree with what you say.

I would point out that every time I've had to make such a change, and 
with the recent ZODB change by Jeremy and Barry, there's been a post on 
this mailing list asking whether anyone needs an upgrade script.

To the best of my knowledge, no-one has said they need one. So, if there 
is no actual need for script, why write such a script?

I think it would be more practical to set a time after which people will 
definitely not need to toss a Data.fs, although an upgrade script would 
be acceptable. I don't think that time is quite yet.

--
Steve Alexander