[ZODB-Dev] Support for graceful ZODB Class renaming
Pieter Nagel
pieter@nagel.co.za
Sun, 19 Jan 2003 16:19:55 +0200
On Sun, Jan 19, 2003 at 02:30:24PM +0100, holger krekel wrote:
> interesting approach. Do you also cope with exported data (say to
> xml) which gets reimported later when the scheme has already changed?
>
> Do you have a history list of Migrators that would get applied?
I assume you mean you backup your database to an export file periodically,
and you want to reimport the backup at a future date after the schema has
undergone N development iterations of change.
The answer is no. This far I only needed to handle the case where N=1, and
so I only keep one Migrator at hand.
It should be easily doable. You need to store a numerical schema version
in the database, keep the current schema version in the code, and keep a
list of all Migrators that you ever used in the code.
Then combine & run all the Migrators from V to current; where V is the
schema version stored inside the exported file.
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