Tobias,
To turn the question round - what unique features of MonetDB could be
exposed through SDB to yield a better RDf store?
The current design covers the current set of databases supported but
it's not fixed - maybe there is something especially useful in MonetDB
and maybe it needs an extension to the design. The design is based on
templating via all those classes (the instance for each database is a
small class). The SQL generator usually needs some per-DB work because
SQL databases aren't exactly very "standard".
Andy
On 25/08/11 21:28, Paolo Castagna wrote:
Hi Tobias,
first of all, welcome on jena-users mailing list.
Tobias Willig wrote:
Hi everyone,
I like to add support for MonetDB in SDB and I have two questions concerning
this project:
1. How much effort it takes to add support for a new database type?
It requires some effort. You need to add new Java classes and the necessary
tests.
Have you checked out the SDB sources yet?
If not:
svn co https://svn.apache.org/repos/asf/incubator/jena/Jena2/SDB/trunk/ SDB
cd SDB
mvn test
You can use Eclipse and search for "Derby" which is one of the DBMS supported
by SDB. This way you'll find the list of Java classes in SDB to support Derby.
Then, you can read and study those classes. While you do that, you'll learn the
design of SDB and you will get an idea on what it is required to add MonetDB.
2. Are there predefined extension points that allow adding a new database
type easily?
Yes, there are. Look at the super classes and interfaces from the list of
classes above (i.e. searching for "Derby").
There isn't an "how to add a new database to SDB" guide, however make sure
you read the general SDB documentation (it does not hurt).
Also, if you want to contribute an "how to add a new database to SDB" you
are more than welcome to do so.
If so could you give me the name of some classes and config files, which
are important to accomplish that task?
You can start from:
GenerateSQLDerby -- extends --> GenrateSQL
FormatterSimpleDerby -- extends --> FormatterSimple
StoreSimpleDerby -- extends --> StoreBase1
FmtLayout2HashDerby -- extends --> FmtLayout2
StoreTriplesNodesHashDerby -- extends --> StoreBaseHash
TupleLoaderHashDerby -- extends --> TupleLoaderHashBase
FmtLayout2IndexDerby -- extends --> FmtLayout2HashDerby
StoreTriplesNodesIndexDerby -- extends --> StoreBaseIndex
TupleLoaderIndexDerby -- extends --> TupleLoaderIndexBase
Also look at:
- JDBC.java
- DatabaseType.java
- StoreFactory.java
- SDB.java
And the existing tests.
May I ask you what motivates you in adding MonetDB?
I've never used it myself and, indeed, I use TDB instead of SDB.
Transactions are coming, hopefully in the 0.9.0 release of TDB.
Last but not least, it's not only about the code. You should be willing
to support the users of your code too. Once you add support for MonetDB,
people will start using it and, as they use your code, they'll find bugs
and they'll ask you for more features, eventually. You should be willing
to put some effort in fixing the bugs, at least... and you can always say
"no" politely to new features. Until, someone else, who really needs the
new feature and he/she is willing to put some effort, will take over and
push the software a step further.
Once you start, you might have more specific questions on SDB design.
You can post your questions here or on [email protected]
mailing list. The more you demonstrate you put some effort the more
likely you'll receive helpful answers back from the SDB developers.
If you don't put enough effort and expect others will do it for you,
I am afraid, you risk to have not much back.
To conclude, it you are motivated and you think you'll have fun doing
it (and you need it for your work): go ahead, it's not a terribly huge
task and it could be a nice contribution (in particular for all the
MonetDB users out there).
Paolo
Thanks in advance!
Best Regards
Tobias Willig
