The link below is to quite a fascinating article that on the surface is about why Uber moved to MySQL from PostgreSQL.
What it really is about is a severe limitation in how PostgreSQL indexes are updated.
With SQL Server, if you update a few columns in a row, only the indexes that have that column are updated. In PostgreSQL, all indexes still need to be updated. I understand why they've done that but it's not a good outcome.
SQL Server shines in this regard.