
Small vendor
With a very limited support / development staff. They are far more interested in adding new features and fixing bugs than widening the number of databases they support.
When we started using them 6 years we were one of their 1st customers. They were a SQL Server ONLY shop. We practically forced them to move to support Oracle because SQL Server was too small / flaky to handle our requirements. So they already did this type of move, just for us. Since we resell their software into large companies, our argument was the large company already had Oracle and would not install / support SQL Server just to run their product.
It was incredibly painful dealing with this app. It generated SQL Server specific SQL. It used asyncronous ODBC connections, which never worked with the Oracle ODBC drivers, at least not for the 1st 2 years. I went though 6 seperate 3rd party ODBC driver test installs and QC. Sometime they would work for weeks until breaking in a strange way. The whole time the vendor said: Sure, send me everything you have and we will try to recreate. 2TB of data!!!! Of course we couldn't, so they would PCAnywhere into the PC running their software and try to fix it that way.
I'm speaking from EXPERIENCE here, not some BS "oh, it is well supported and has threads, ooooo". Try blowing MONTHS getting multiple systems playing nicely together.
We can't do the reverse, since we can't hold the carrot of SAB-DB already in the large corporations being used as a general database. Unless you want to point be to the companies using it already. Not vendors who support it, companies that use it.