[Zope3-dev] Tossing Data.fs considered harmful

[Tres Seaver]

On Sat, 2003-03-15 at 13:08, Steve Alexander wrote:
> 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.


Jeremy's note about the opaque pickles said, "If this is going to cause
anyone heartache, please let us know ASAP."  I did not construe that as
an offer to write a conversion script, but rather as an offer to
negotiate about when the branch would land.

My claim is that we can't continue assuming that it is OK to make people
toss content or TTW code;  nobody will actually start using Zope3 "for
real" until we promise that such events won't keep happening.  Note that
the final line of Jeremy's note was:

  We are planning one or two more changes down the line that may also
  cause format incompatibilities.  Our goal is to get those changes
  finished as soon as possible.

I don't want to be in the middle of a sprint and have to scrap work
because another such change lands;  even more than that, I want to be
able to work with applications I am building without worrying about this
any longer.

Tres.
-- 
===============================================================
Tres Seaver                                tseaver@zope.com
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