On Tue, Sep 25, 2012 at 12:36 PM, Andreas Jonsson <[email protected]> wrote: > 2012-09-25 12:12, Vincent Massol skrev: >> FTR Hibernate 4 supports multi-tenance: >> http://docs.jboss.org/hibernate/orm/4.1/devguide/en-US/html/ch16.html > > That looks useful, but the database or schema seems to be fixed per > session. Do we not need to access entities from different wikis within > the same session?
We do. If it's really strongly associated to the session we can't use that. > > > /Andreas > >> >> -Vincent >> >> On Sep 25, 2012, at 12:06 PM, Andreas Jonsson <[email protected]> wrote: >> >>> 2012-09-25 10:48, Denis Gervalle skrev: >>>> On Tue, Sep 25, 2012 at 1:29 AM, Andreas Jonsson <[email protected]> >>>> wrote: >>>> >>>>> 2012-09-24 17:26, Vincent Massol skrev: >>>>>> Hi devs, >>>>>> >>>>>> I was trying to make XEM work with HSQLDB and... I have succeeded :) >>>>>> >>>>>> The only problem I have is that DBCP doesn't seem to work with >>>>> Hibernate. For some weird reasons when we do a SET SCHEMA it makes calls >>>>> to >>>>> fail afterwards. In any case if I configure Hibernate to not use DBCP all >>>>> work just fine. >>>>> >>>>> Funny coincidence! I was just trying to get it to work with >>>>> PostgreSQL. It mostly works, as already commented on the Jira issue. >>>>> The only thing that seems to work unreliably is the initial template >>>>> creation. It seems likely that it is the same issue. >>>>> >>>>> But having looked into this I'm a bit worried about the current XEM >>>>> implementation. >>>> You should, we really do scary stuff to support multiple DB, and also >>>> dynamic mapping. >>>> >>>> >>>>> I'm not an expert on Hibernate, but to me it seems that >>>>> entities are expected to be bound to specific tables at initialization >>>>> time. So I'm wondering, does Hibernate really support changing the >>>>> mappings by switching databases or schemas underneath? >>>> The tricks is that we do not really support multiple hibernate mapping. All >>>> accessed DBs use the same mapping. These are serious limitations in >>>> multi-wiki mode for mapping related features. >>>> >>>> Hibernate does not even knows that we switch the DB under its feet. Even >>>> the pool provider is not aware. This is why we need to set the correct DB >>>> each time we open a session/transaction (always tight together), which >>>> means getting a connection from the pool. We do not support nested >>>> session/transaction, in particular to different DBs for the same reason. >>> Thank's for your reply. Maybe I've got a correct impression of the >>> current state of affairs. >>> >>> I guess this issue will be addressed in the new model implementation, >>> but I was thinking of this solution, which seems to be possible with a >>> reasonably small effort and with full backwards compliancy: >>> >>> Re-register the entity mappings for each wiki, adding a wiki-specific >>> prefix to each entity name. Then let a custom EntityNameResolver add >>> the prefix by taking the current database from the execution context. >>> >>> For instance, templates could be prepared for entity mappings like so: >>> >>> <class name="${entityNamePrefix}:com.xpn.xwiki.doc.XWikiDocument" >>> table="xwikidoc" schema="${entitySchemaAttribute}"> >>> >>> And then the SessionFactory is rebuilt whenever a wiki is created or >>> deleted. I'm a bit confused on how and when custom mappings are >>> "injected", and there might be other things that I've missed. >>> >>> But on the other hand, aren't there any frameworks that can do this? >>> What about Hibernate Shards? >>> >>> Best regards, >>> >>> /Andreas >>> >>> >>> >>>>> What prevents it >>>>> from generating prepared queries for accessing the entities, which will >>>>> be resolved against the initial database/schema, and continue to use >>>>> these even after the database or schema changes? >>>>> >>>> Our config prevent using prepared statements on the DB server. >>>> >>>> >>>>> +1 for your action plan. >>>>> >>>>> Best Regards, >>>>> >>>>> /Andreas >>>>> >>>>>> I've googled around and found that there are lots of people complaining >>>>> about DBCP. >>>>>> I've googled for what connection pooling library to use and I've found >>>>> that most people are recommending BoneCP (http://jolbox.com/). >>>>>> See: >>>>>> * >>>>> http://stackoverflow.com/questions/5640146/java-jdbc-connection-pool-library-choice-in-2011-2012 >>>>>> * http://www.jorambarrez.be/blog/2012/04/30/dbcp_vs_c3p0_bonecp/ >>>>>> * >>>>> http://stackoverflow.com/questions/8057110/java-database-connection-pool-bonecp-vs-dbpool-vs-c3p0 >>>>>> The other thing is that we currently have some 300 line of code that we >>>>> shouldn't have at all and that we need in XWiki just for handling DBCP >>>>> (see >>>>> com.xpn.xwiki.store.DBCPConnectionProvider). >>>>>> The pro of BoneCP is that it seems to be the fastest, see >>>>> http://jolbox.com/benchmarks.html >>>>>> So here's what I'd like to propose: >>>>>> >>>>>> * We move DBCPConnectionProvider to a legacy module >>>>>> * We bundle the bonecp jar by default >>>>>> * We configure our hibernate.cfg.xml by default to use boneCP: >>>>>> >>>>>> <property name="bonecp.idleMaxAge">240</property> >>>>>> <property name="bonecp.idleConnectionTestPeriod">60</property> >>>>>> <property name="bonecp.partitionCount">3</property> >>>>>> <property name="bonecp.acquireIncrement">10</property> >>>>>> <property name="bonecp.maxConnectionsPerPartition">60</property> >>>>>> <property name="bonecp.minConnectionsPerPartition">20</property> >>>>>> <property name="bonecp.statementsCacheSize">50</property> >>>>>> <property name="bonecp.releaseHelperThreads">3</property> >>>>>> >>>>>> <property >>>>> name="connection.provider_class">com.jolbox.bonecp.provider.BoneCPConnectionProvider</property> >>>>>> What this means: >>>>>> * Existing users of XWiki will not have to change anything, it'll still >>>>> work >>>>>> * New users will use bonecp without knowing >>>>>> * Existing users can migrate to bonecp just by changing one line in >>>>> their hibernate.cfg.xml file >>>>>> I'd love to do this for 4.3 but we're already quite advanced in the 4.x >>>>> cycle. That said it's just a one line change in hibernate.cfg.xml in case >>>>> of problem to go back to DBCP so we could do this for 4.3 which leaves us >>>>> 4.3, 4.4 and 4.5 to test this out. And if later on we find an issue we'll >>>>> always be able to release a 4.5.1 that has this one line change to go back >>>>> to DBCP. >>>>>> WDYT? >>>>>> >>>>>> Here's my +1 for this action plan. >>>> Unless BoneCP really provide proven improvements, and not only a potential >>>> performance increase, that will probably not be tremendous, I am not really >>>> in favor of changing a well-know Apache project for a project that as not >>>> really a great team of supporter. From the project info page, I see only >>>> one name. From the forum, there seems to be serious rumors that the project >>>> is no more supported by that guy since more than a year. >>>> >>>> So, currently, I am -1. >>>> >>>> >>>>>> Thanks >>>>>> -Vincent >>>>>> >>>>>> _______________________________________________ >>>>>> devs mailing list >>>>>> [email protected] >>>>>> http://lists.xwiki.org/mailman/listinfo/devs >>>>>> >>>>> _______________________________________________ >>>>> devs mailing list >>>>> [email protected] >>>>> http://lists.xwiki.org/mailman/listinfo/devs >>>>> >>>> >>> _______________________________________________ >>> devs mailing list >>> [email protected] >>> http://lists.xwiki.org/mailman/listinfo/devs >> _______________________________________________ >> devs mailing list >> [email protected] >> http://lists.xwiki.org/mailman/listinfo/devs >> > > _______________________________________________ > devs mailing list > [email protected] > http://lists.xwiki.org/mailman/listinfo/devs -- Thomas Mortagne _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
