Hi to all, more thoughts on database persistence ...
It seems having a jdbc based persistence manager as the default implementation misleads users, new and not so new users often think that jackrabbit will benefit from rdbms features and analyze jackrabbit internals taking into account j2ee best practices. Keeping simple the SimpleDBPersistenceManager is a good option not only for the sake of simplicity, but also because other approaches are discouraged due to design decisions. As Stefan pointed a few times jackrabbit is designed to stand in its own right. It means that it's not designed to leverage any persistence storage engine, rdbms included. The fact derby is the default PM doesn't mean it's the best option, there's overhead related to sql parsing and too many unused features. It took me a while to understand it :), but I agree that for now the best option is a simple and transactional btree implementation, as Stefan has been pointing for a long time. Something like http://jdbm.sourceforge.net/ would probably be a better fit. Stefan, WDYT?. Is it worth to give it a try? Since questions about leveraging rdbms capabilities arises in the Mailing list all the time, in case the comments above have any sense, I suggest adding a few more entries to the faqs that make clear Jackrabbit is not just a layer on top of a rdbms. WDYT? e.g. ---- I want to use jackrabbit in a j2ee environment and I want to use JNDi to configure jdbc connections, how can I do it? You can override the default implementation and get connections through JNDI, but take into account that using a rdbms in server mode is not the best option. Jackrabbit *is* a storage engine by itself. Does Jackrabbit leverage rdbms capabilities? No, all Jackrabbit needs from a PersistenceManager implementation is a simple transactional persistence mechanism that supports large collections. A simple btree implementation suffice. What's the benefits of using a jdbc based PM implementation? Only the rdbms administrative stuff, scheduled backups, etc. --- my 0,0002 cents, in case it worths that much ;) edgar ps, congratulations to all. you are all doing a great job!! On 3/18/06, Jukka Zitting <[EMAIL PROTECTED]> wrote: > Hi, > > On 3/18/06, Stefan Guggisberg <[EMAIL PROTECTED]> wrote: > > 'Simple' also refers to use of a very simple data model instead of > > a fully normalized schema or some object-relational mapping. > > Agreed. A different data model would require a fully separate PM class > (like in the orm- or dbd- contribs). I believe the > SimpleDbPersistenceManager data model is good for the current needs > and pretty much orthogonal to the way the database connection is > handled. > > > those best practices apply to j2ee applications. the point is that i don't > > consider jackrabbit to be a j2ee application, jackrabbit is infrastructure > > and has other requirements regarding its persistence layer than a > > database application. > > Good point. In many cases Jackrabbit however lives in a J2EE > environment and, as expressed in JCR-313, there are legitimate needs > for using it within the constraints of existing database deployments. > > > note that write operations must occur within a single transaction, i.e. > > you can't get a new connection for every write operation. > > Ah, good point. That pretty much downs my proposal. So, withdrawn for now. > > BR, > > Jukka Zitting > > -- > Yukatan - http://yukatan.fi/ - [EMAIL PROTECTED] > Software craftsmanship, JCR consulting, and Java development >
