26 Jan
2012
26 Jan
'12
11:34 p.m.
Hi Roman,
On Thu, Jan 26, 2012 at 21:53, Roman Muntyanu <rmuntyan(a)softserveinc.com>wrote;wrote:
Hi Denis,
Just of curiosity, how did you choose liquibase from the rest? E.g.
http://code.google.com/p/dbmigrate/
http://www.dbmaintain.org/overview.html
http://code.google.com/p/flyway/
and etc ...
What were pros and cons?
Thanks for asking.
All of the one you mentioned does not provide the most important
IMO: database agnosticism.
You may also add Solidbase and AutoPatch to your list.
Moreover, Liquibase provide an interesting extension for hibernate, and if
we drop the hibernate schema update, we will need it to produce the script
to support our older databases. The Liquibase API seems also more fine
grained and clearer IMO. I do not want a complete black box and I already
have the migration mechanism in place for data.
The best will be the tool that integrate with it and provide the same
database isolation that hibernate provide for data, else I could simply
written the proprietary scripts in my existing system. If you know some
that really compete with liquibase, let me know.
Regards,
Roman
-----Original Message-----
From: devs-bounces(a)xwiki.org [mailto:devs-bounces@xwiki.org] On Behalf Of
Denis Gervalle
Sent: Thursday, January 26, 2012 21:29 PM
To: XWiki Developers
Subject: [xwiki-devs] [Proposal] Use liquibase to manage the database
schema
While trying to reduce the likelihood of duplicate ids for documents, and
extending my patch to provide a proper solution for objects, I fall on a
really unexpected issue: the type of the object identifiers are Integer
where those of documents are Long. This is completely abnormal since we
have several objects per documents, and therefore we need more distinct ids
for objects than documents.
I have therefore upgraded the ids of objects to use Long, and provide an
implementation that use the lowest 64bits of an MD5 key for object in the
same way I do for documents. This implementation introduce two new
serializer: UidStringEntityReferenceSerializer and
LocalUidStringEntityReferenceSerializer.
I have also bridged the statistics that derived from objects. The new
implementation works perfectly on a new database but...
... I am unable to provide a proper migration procedure, since hibernate
cannot manage changing the types of existing columns. It does not complains
during schema update, it simply do nothing about them. And later the data
migration breaks since my hashes cannot fit in the database properly. After
thorough googling, I understand that hibernate schema updates were not made
for production use and are really limited opposed to the general idea we
had of it.
Since I am currently stucked, I propose to move ahead and use a new tool
to properly manage our database schema upgrade:
http://www.liquibase.org/
Liquibase is Apache licensed and provide a database agnostic version
system for migrating databases. It does not works like a diff tool, but
more like a patch tool, where you provide several XML description of your
wanted changes and it manage to apply or rollback there changes in an
ordered manner to upgrade the database to the latest schema.
There is several way to apply these changes and I would like to see if it
could be integrated in our current migration procedure, or at least as an
independent listener.
WDYT ?
--
Denis Gervalle
SOFTEC sa - CEO
eGuilde sarl - CTO
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--
Denis Gervalle
SOFTEC sa - CEO
eGuilde sarl - CTO