PolyBase: Support String Columns For Predicate Pushdown
Predicate pushdown to Hadoop sources in SQL Server 2017 and 2019 CTP 2.2 works for date, time, and numeric data types (as the documentation at https://docs.microsoft.com/en-us/sql/relational-databases/polybase/polybase-pushdown-computation?view=sql-server-2017 correctly notes). It would be great if we could also push down string predicates from VARCHAR or NVARCHAR data types.
Supporting LIKE filters would be nice, but even exact matches and support just for what's covered for numeric data types could help.
Marcel Bechmann commented
We have the same request for MongoDB as datasource
not just to Hadoop sources - what about any data source (including relational - other SQL Server, Oracle, etc...)