The SQL Server is only hosting 2 databases currently, and the largest is the one moving, so thresholding SQL back so they share resources shouldn't be a problem.

Babelfish enables PostgreSQL to understand database requests—both the command and the protocol—from applications written for Microsoft SQL Server without changing libraries, database schema ...

The two databases have been fighting for fourth place (behind Oracle, MySQL, and SQL Server) for many years, but PostgreSQL now has a solid lead over Mongo. PostgreSQL is the oldest open-source ...