We are currently using MySQL for a product we are building, and are keen to move to PostgreSQL as soon as possible, primarily for licensing reasons.
Has anyone else done such a move? Our database is the lifeblood of the application and will eventually be storing TBs of data, so I'm keen to hear about experiences of performance improvements/losses, major hurdles in converting SQL and stored procedures, etc.
Edit: Just to clarify to those who have asked why we don't like MySQL's licensing. We are developing a commercial product which (currently) depends on MySQL as a database back-end. Their license states we need to pay them a percentage of our list price per installation, and not a flat fee. As a startup, this is less than appealing.
We did a move from a MySQL3 to PostgreSQL 8.2 then 8.3. PostgreSQL has the basic of SQL and a lot more so if your MYSQL do not use fancy MySQL stuff you will be OK.
From my experience, our MySQL database (version 3) doesn't have Foreign Key... PostgreSQL lets you have them, so we had to change that... and it was a good thing and we found some mistake.
The other thing that we had to change was the coding (C#) connector that wasn't the same in MySQL. The MySQL one was more stable than the PostgreSQL one. We still have few problems with the PostgreSQL one.
I have done a similar conversion, but for different reasons. It was because we needed better ACID support, and the ability to have web users see the same data they could via other DB tools (one ID for both).
Here are the things that bit us:
That said, once it was in place and tested, it was much nicer. With correct locking for safety reasons and heavy concurrent use, PostgreSQL performed better than MySQL. On the things where locking was not needed (read only) the performance was not quite as good, but it was still faster than the network card, so it was not an issue.
Tips:
Steve, I had to migrate my old application the way around, that is PgSQL->MySQL. I must say, you should consider yourself lucky ;-) Common gotchas are:
I hope that helps at least a bit. Have lots of fun playing with Postgres!