SQL Server has a feature called Indexed Views that are similiar to materialized views.
Basically, the Indexed View supports COUNT/SUM aggregate queries. You create a unique index on the Indexed View and SQL Server automatically keeps the COUNT/SUM upto date. Doing the same thing in Postgresql using Materialized views is slow and the developer has to manually issue a "refresh materialized view" command. The alternative is to write additional sql to update count columns....uneccessary work.