not everything running in RAM which then needs transaction logs writes to disk. In RAM, transactions are already committed. If you machine dies, or VM moves from RAM to RAM, you lose your commits. VERY VERY BAD.
PostgresSQL is a mature database product and used all over the world. Instead of spending money on Oracle or SQL Server, invest the money back into PLM, IT infrastructure or additional resource to support the PLM solution.
It's been over 3 years of using, implementing and supporting SQL Server with Windchill 9.1 and 10.1 with PTC Technical Support. It's just been a horrible experience supporting this. It was an easy way to convince the executives to move from Oracle to SQL Server but it really kills the maintainability, performance, scalability and support which should be the backbone of implementing any database.
I even attended some SQL Server DB courses and explained to the other SQL Server DB admins who handle some databases both Oracle and SQL Server my environment of over 3 million records. They all told me, why did you go to SQL Server. I should have stayed with Oracle. Everyone in the class including the SQL Server Trainer, who has been teaching and support SQL Server since it's birth, advised me that I shouldn't migrate for large databases 2 million+ records and large amounts of columns in a table because it can be over 8K especially with multi-byte characters (different languages).
Don't listen to all the sales flyers and propaganda, the true experienced experts warned me about SQL Server.
Just like Linux supported by RedHat, Linux has now become the most stable, cost-effective OS server platform. I hate rebooting my servers 1/week because it just adds headaches and overhead to suppport. (i.e. Windows OS with Windchill).