kdb+ from Kx systems is popular among users who have mostly tick data (billions of trade/bid/offer updates). It has bare bones SQL, and its own query langauge "

kdb+ from Kx systems is popular among users who have mostly tick data (billions of trade/bid/offer updates). It has bare bones SQL, and its own query langauge "q" which in many cases simplifies the queries immensely (with two features, "foreign key chasing" and "as-of joins" which are somewhat at odds with Codd's original pure relational model so are unlikely to get into the SQL standard)