Microsoft will only deploy on Microsft.
Some tests a few years ago showed the then current version of SQL Server (6.0 I think) against MySQl 3.xx and Oracle.
In a variety of speed tests, SQL Server was (from memory) about 9 times slower and Oracle over 20 times slower.
With the open development methods and platform independence, MySQl & PostgreSql are streets ahead of anything else for 'normal' commercial use. By which I mean complex databases up to 1 Terrabyte.
Easy to backup too, with simple file snapshots at regular intervals.
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