I have a related question. I assume SDB is based on SQL as the database access language. TDB has its own triple store representation, which I understand is much faster than SDB/RDBMS, but has some limitations from an update concurrency standpoint. Do both SDB and TDB build on top of a common core interface? If one had a non-SQL DBMS that potentially offered high performance, if this common core interface exists, would it be an appropriate interface to build an implementation to a non-SQL database? Or would making lots of alterations to TDB be necessary?
One other question. If an application has a set of ontologies it uses, some of which are large and never change, some of which do require concurrent updates, can one have an application that opens a model in TDB, then opens a model from SDB, then combine these two models together? Would this allow one to take advantage of the TDB high-performance for the read-only ontologies, while still getting update capabilities for the ontologies in SDB? -----Original Message----- From: Andy Seaborne [mailto:[email protected]] Sent: Thursday, September 01, 2011 3:37 AM To: [email protected] Subject: Re: Adding support for MonetDB 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 >>
