On 15/04/2008, at 10:07 PM, Andrus Adamchik wrote:
Sure, but I think the fact that we'll get more metadata in Cayenne
will not make DBPatch obsolete. Cayenne schema merge can only
operate on a delta of two schema versions. DBPatch also deals with
data migration. So the two serve different goals. DBPatch is about
DB "versioning" across multiple installations of a DB.
Yes, we thought that if we ever reached a goal of versioning through
storing multiple Cayenne models, that we'd still need a post-schema-
update hook to run SQL needed for the data upgrade.
I haven't thought through the cross-DB features just yet... Maybe we
can implement a mechanism based on defaults (e.g. if 90% of
dbpatches do not depend on a DB nature, you create them once, for
the remaining 10% you'd create files following naming
conventions ... mypatch.sql.mysql, mypatch.sql.derby, etc.)
We found that lots of things had to be changed between DBs. VARCHAR ->
VARCHAR2 in Oracle, VARCHAR(5000) in Derby -> TEXT in mySQL. Different
ways of dropping and creating indexes, etc. The differences are
substantial. Our initial idea was preprocessing statements:
#mysql
CREATE TABLE....
#end
But it seemed like too much work for the reward, so we just settled on
folders full of (almost) duplicate files. Keep an eye out for a commit
from Matthias later this week to onCourse which will implement all this.
My only other comment here is that ant may not be the best tool for
deployed systems.
Regards
Ari
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