ObjectWeb has announced the release of C-JDBC 1.2, their open source database clustering middleware. The new release includes support for Updatable ResultSets, new pass-through schedulers for increased performance as well as many other improvements and fixes.

To use C-JDBC, databases are replicated to a set of servers, and C-JDBC is configured to know each element in this database "cluster." Reads passed through C-JDBC are then load-balanced across each node, with writes being broadcast to each node to maintain synchronicity.

Among other changes, the 1.2 release supports Updatable ResultSets. New pass-through schedulers have been added for all RAIDb levels for increased performance. The DatabaseMetaData code has been refactored to provide more transparency with regard to the underlying database engine. A number of other contributions have helped in various area for developer documentation, code cleaning and bug fixes.

This project enables a middleware component to replicate many features of a database cluster, which might be very useful if a formal DBA isn't available or the database product being used doesn't support clustering.

What do you think?

anyone using this in the field yet? in the comments on TSS after the last release, there seemed to be people interested in trying it out, have any of them tried it in a production environment yet?

Sounds interesting, do they have support for jdbc 3 or does it plug to existing driver or has it's own api

Sounds interesting, do they have support for jdbc 3 or does it plug to existing driver or has it's own api

You can consider C-JDBC as a smart JDBC proxy and therefore we support the same set of features as your database driver does (if your driver does not support JDBC 3, we don't either).
However we do not support yet JDBC 3 savepoints. You can check the documentation for a detailed list of limitations.

Emmanuel

anyone using this in the field yet? in the comments on TSS after the last release, there seemed to be people interested in trying it out, have any of them tried it in a production environment yet?

I tried to get JDBC running (the previous release, as well as a couple before that). The DB I use is PosgreSQL 7.4 on Linux. To test how stable the system is, I tried to disable one DB node from the cluster, and later tried to enable it again. At a first glance this actually seems to work, but the devil is in the details. It doesn't work under load!

If you're doing inserts to your DB cluster (at a higher rate than +- 1 per second), then it simply doesn't work anymore. When enabling the previously disabled node I'm getting a duplicate row SQL error.

So, the conclusion must be that either I'm doing something completely wrong (although I tried with a very simple test case and followed the instructions step by step), or that JDBC is simply not ready for production yet.

Although this naturally can't be changed anymore, I assume it would have been better as ObjectWeb had more accurately reflected the state of its software in the version number. Although CJDBC looks *very* promissing and the developper seems to be very motivated and skilleed, maybe calling it version 1.2 is too optimistic and something like 0.6 orso would have actually been better.

This is really cool stuff! I am just wondering like others, could someone who used this before shared his experiences with the TSS community?

thx

rgds
tmjee

Is not a winderfull software, have problems with fail over and syncronization. When a database goes off we must go their and do a cople os things to restore de database :(

with postgres i must do pg_dump from the god database (the one do not goes off), and restore this dump in the other database. :(

This cold be done automacticly, when c-jdbc do this they come a nice software.

Now is a god software to have fail over in the databeses with a low budget.

C-JDBC and heartBeat(piranha) together is a good solution :) for small projects

This is really cool stuff! I am just wondering like others, could someone who used this before shared his experiences with the TSS community?thxrgdstmjee

As C-JDBC was not backed yet by any company, it is really hard to get feedback on real usage and C-JDBC is mostly raw technology. We will try to change that with Emic Networks, the company I just joined.
There is an interesting thread on Javalobby that discussed the results of the C-JDBC survey. I think that Andy DePue's response is insightful.

Emmanuel

I was also interested and I tryed it 3 month ago. I make one simple example where I was running simple inserts against 2 databases. However c-jdbc doesn't work as expected. Some rows was lost in one database. I couldn't imagine use it in this state in real production environment event in middle scale projects.
Also administration interface is far from error prone. It doesn't warn you when you are doing strange operations.

However c-jdbc doesn't work as expected. Some rows was lost in one database.

Did you report that on the mailing list? I would be surprised that this would not have been addressed if it was reported. If users don't provide feedback, a project cannot improve.

Also administration interface is far from error prone. It doesn't warn you when you are doing strange operations.

Yes, this is true. The admin interface is very open so that you can have fine grain control on the C-JDBC controller. However, you have to be careful on what you do else you can break everything very easily. We are trying to refine these functionalities to restrict what is available from the admin console. Most of the problems raised are due to a misuse of the technology but our documentation is not that great so the users are not to blame here.

Don't hesitate to share your feedback (positive or negative) on the c-jdbc at objectweb dot org mailing list, it helps us improve the quality of the technology.

Emmanuel

Anyone know some success stories about the use of C-JDBC product?

Should be available a good presentation I've seen at the the last ApacheCon 2004 in LasVegas...

bye,
Luca Garulli
www.Pro-Netics.com (member of Orixo.com - The XML business alliance)
OrienTechnologies.com - Light ODBMS, All in one JDO solution