[ZODB-Dev] Preventing a folder from being packed

[sean.upton at uniontrib.com]

But this also puts burdens on the app developer to get the txn metadata
right... one slipup in get_transaction().note(), and things are a mess?
Perhaps this is a bit over-dramatic...

-----Original Message-----
From: Jeremy Hylton [mailto:jeremy at zope.com]
Sent: Thursday, May 15, 2003 10:51 AM
To: sean.upton at uniontrib.com
Cc: Toby Dickenson; dheltzel at adolor.com; zodb-dev at zope.org
Subject: RE: [ZODB-Dev] Preventing a folder from being packed


On Thu, 2003-05-15 at 13:48, sean.upton at uniontrib.com wrote:
> Forgive my ignorance, but wouldn't this be a bit of work?  Since ZODB
> essentially just persists objects and references, I wonder how much of a
> mismatch and additional complexity the Zope-level notion of
> folders/containment hierarchies would add to the storage.  How smart
should
> the storage be?  I like the per-class adjustment of history, because this
> maps well in and out of Zope, but wouldn't notions of containment be
harder
> to preserve?  

Here's an unbaked idea.

I think it could work on a per-transaction basis by using transaction
metadata that was written by the application and read during pack.  This
would keep more revisions than necessary in many cases; a txn modifies
two objects, one that it wants revisions for and one that it doesn't. 
The practicality of the approach depends in part on how likely an
application is to modify a mix of objects in a single transaction.

Jeremy