On Thu, Oct 12, 2006 at 07:40:42PM +0200, Tim Tassonis wrote: > > I have yet to see a good application that supports "database > independence". > > If you are talking about high- end applications (big databases with lot > of transactions), you're of course right. However, there are a lot of > applications with small or medium sized databases and not so many > transactions, where you don't need to get the best out of your RDBMS for > decent performance. > > With a good design and some expierience in portability in general, you > will be able to write a good, "quite" database independent application, > supporting some of more standardized RDBMS's. Actually, back when I worked at http://ud.com we had a fairly complex database that could see a heavy transactional load and was actually quite database independent (we developed on DB2, supported Oracle, could have supported MSSQL and at one point actually had it running on PostgreSQL). The application made extensive use of functions/stored procedures, constraints, RI, and triggers. How did this miracle occur? Well... the database code itself wasn't actually database independent. It was generated by a bunch of XSLT that we developed (we called it 'datadef'). In addition to generating database generation code (SQL), it generated C accessor functions (much of the code was in C), documentation, and some other things. In fact, it even had the ability to generate code in a language it could understand. This allowed us to do enums in such a way that the C code had a real enum type, and the database had a table that stored the same information. You could then refer to that enum anywhere in a table definition in datadef, and an appropriate field definition would be created, complete with RI back to the appropriate parent table. Sadly, my understanding is that management didn't want datadef open-sourced. But you can actually write good code that will run on multiple databases if you're willing to write the tools to allow you to do it. -- Jim Nasby jim@xxxxxxxxx EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
