Yes, This is *very* useful. It's exactly what we need for databases we haven't tested XWiki on. So any field of more than 4096 should be converted to "text" in hibernate.cfg.xml (which should be compatible with mysql and the databases xwiki already works on). Oracle9Dialect should be use (does it mean forgeting support for Oracle8 ?) Text fields of more than 4096 cannot be handled using "like" so using the Lucene plugin is mandatory for Oracle Ludovic David Delbecq a écrit :

Reporting, out of my mind of months ago, for Oracle

- First, oracle does assume an empty string same as null, this has 2 majors implications * The 'not null' String elements can get nulled when stored on database, triggering lots of hibernate exception when they are retrieved again. The 'not null' should be removed from String and all string getters in the bean should do something like return (value==null?"":value). Only exception to this should be keys, but keys can not be empty strings either. Oracle 10, i think is supposed to have this problem fixed and nulls are no more same a empty strings. However, oracle 9 here. * Another point, in sql, any boolean expression which implies a null is systematically evaluated to 'false'. As a result, the SQL query expression ":var1 not equal :var2 " is always evaluated to false if any of :var1 or :var2 is an empty string on oracle. A workaround at that time was to hunt expressions involving non key Strings and replace them with more complex expression taking into account null cases - Oracle is quite limited in the way it handles muliple lobs column in the same table. The hibernate mapping of xwiki uses String of length > 4096, this is converted to the type "TEXT" in oracle language. A TEXT has nearly the same behaviour as a varchar in oracle, meaning it can be used as a string in expression. However, there can be only one TEXT field per row. When there were several String of length >4096 in hibernate, they were all blindly converted to oracle TEXT type. The database of course refused to create such tables. Another alternative is clob (Character Large Object), you can have several on same row, however they do not act like varchar (you can't use them like that in sql expression). Hibernate oracle language does most of converting job (take care there 2 hibernate languages, the one to go was oracle9Dialect) when you chose the hibernate type 'text' instead of String. - Then, there is no initial database for oracle. At the time i did all my tests and patchups, i didn't know either there was a sample database for mysql. Because i was lacking more development time, it has been less time expensive for to drop our oracle patch ups everywhere and to switch to a mysql environment, thought we mainly prefer to concentrate as much as possible oracle here :)

Hope you find this information helpful

Ludovic Dubost a écrit :

...

Hi,

In order to possibly improve our database support in the future, I would be interested to discuss with any users that have ported XWiki to other databases than MySQL. We are especially interested by databases used by corporations like Oracle, Sybase, SQL Server.

Would any of you that have ported/tried to port XWiki to another database tell us what has worked/not worked and what they have done. That would be great help.

Since we now have the default database of XWiki as XML, we have the possibility to write a script to load this in any database. We just need to make sure that the core behavior of the storage engine is compatible with the target database.

Thanks Ludovic

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