From Data Platform Blog:

Following the release of SQL Server 2016 CTP 2.0 last month, the SQL Server engineering team is excited to announce the immediate availability of CTP 2.1 release for download. The release includes improvements for three new innovations releasing in SQL Server 2016 – Stretch Database, Query Store, Temporal – and Columnstore Index, introduced in SQL Server 2012:

1. Stretch Database, which enables transparent stretching of warm and cold OLTP data to Microsoft Azure in a secure manner without requiring any application changes, includes the following fixes:
   1. Data migration does not trigger lock escalation in stretched tables, so no timeouts for INSERT or SELECT operations
   2. Automatic encryption and validation requirement of remote server certification, preventing “man-in-the-middle” security attacks
   3. Ability to run INSERT statement against updatable views created on top of stretch tables
2. Query Store, the “flight recorder” which stores historical query plans and their performance characteristics, allowing DBAs to monitor and analyze plans and force a specific query plan on regression, includes:
   1. Parse statistics avg_parse_duration, last_parse_duration, avg_parse_cpu_time, last_parse_cpu_time removed from sys.query_store_query view
   2. The minimally allowed for flush_interval_seconds parameter, 60 seconds, is now verified in ALTER DATABASE statement
   3. Naming in sys.database_query_store_options and actual parameters in ALTER statements are in alignment with flush_interval_seconds and operation_mode
   4. Query Store on master and tempdb disabled and error message thrown (“Cannot perform action because Query Store cannot be enabled on system database master (tempdb)”)
   5. Force_failure_count parameter is now cleared after plan is enforced
3. Temporal, which enables handling and analyzing database records that changes over time, includes:
   1. Support for computed columns
   2. Support for marking one or both period columns with HIDDEN flag, allowing for frictionless migration for existing applications. The following applies to HIDDEN period columns:
      1. 1. Column is not returned in SELECT * statements
         2. INSERT statement without column list do not expect inputs for HIDDEN columns
         3. Hidden column must be explicitly included in all queries that directly reference temporal table or other objects that reference temporal table (views, for example)
         4. BULK INSERT scripts that worked with non-temporal table (prior to adding system-versioning and hidden period columns) will continue to work and hidden columns will be auto-populated
         5. is_hidden flag is set to 1 in sys.columns view

4. Columnstore Index includes:
   1. Improved seek performance
   2. Improved scan performance with partitioned tables

Source: Data Platform Insiders