Jens Frank wrote:
MySQL has some strange "enhancements" to SQL
that are not compatible to
the rest of the world. With dammit's port to PostgreSQL, these spots
were identified and using a global ($wgIsPg I think it's named) the
MySQL-specific instructions can be disabled. This should be a good
starting point for a port to Oracle. PostgreSQL handles sequences the
same way Oracle does, so that our usage of MySQL's auto_increment
columns has already been ported, too. The PostgreSQL port is in the
latest 1.3 betas.
I've rewritten most of the PostgreSQL port in my working copy, it hasn't
been committed yet. I'm also changing the way we call the database
throughout the codebase. I'm holding my breath hoping people don't make
too many commits, because at this stage pretty much any change will
cause conflicts. You can see where I'm up to at:
http://www.ph.unimelb.edu.au/~tstarling/half-completed_DB_OOP.patch
I've decided to cut short the OOP and table name modifications, do some
testing, and then commit it, before completing the conversion. It will
still work when it's half-converted.
The problem with $wgIsXxxx was that it would have required just as much
work to implement a port to a third DBMS as it did to implement the
second. Instead of DBMS-dependent conditions scattered throughout the
codebase, I'm working on having common functions which are efficient for
MySQL but can be emulated by any DBMS. I don't know exactly how Oracle
differs from PostgreSQL and MySQL, but hopefully the bulk of the work to
produce a port should be in the DatabaseOracle subclass rather than
throughout the code.
-- Tim Starling