Keeping track of how data changed over time in a table has always been a difficult task. Both data insertion or modification and even querying is just more complex when you what to have the result that was returned when the time is a specific point of time in the past. And even more complex when you’re not looking for a specific point in time, but a period of time. Temporal database theory and temporal operators surely can come to the rescue, but they are not a matter for the faint of heart! Luckily one of the biggest - and most requested – feature that has been added to SQL Server 2016 solves exactly this problem, allowing the creation of change audit trails, data history and point-in-time queries so simple and anyone, even on *current* applications, can benefit from it, simplifying solution architecture and saving time (and money) on maintenance an reporting.

1. SQL SERVER 2016 TEMPORAL
TABLES
Davide Mauri
www.davidemauri.it | info@davidemauri.it
@mauridb

2. DAVIDE MAURI
 Microsoft SQL Server Data Platform MVP since 2006
 Works with SQL Server from 6.5, on BI from 2003
 Specialized in DataArchitectures, Database Design, PerformanceTuning, High-
Performance DataWarehousing, BI, Big Data,Azure Data Platform
 President of UGISS (Italian SQL Server UG) for 10 years
 Regular Speaker @ SQL Server events
 E-mail: info@davidemauri.it
 Twitter: @mauridb
 Blog: http://sqlblog.com/blogs/davide_mauri/default.aspx

3. TEMPORALTABLES
 Automatically keeps track of changed data
 Along with period of validity
 Available in all editions of SQL Server (from the Express!)
 Available in SQL Azure
 ANSI 2011 compliant
 Provide native support for “as-of-time” queries
 Transparent to existing applications (if needed)
 Integrated with existing features (eg: Partitioning, Hekaton)
 Integrated with new features (eg: Stretch Database)

4. LOVE AT FIRST SIGHT!
 TemporalTables

5. TEMPORALTABLES
 Automatically keeps track of changed data (versioning)
 Along with period of validity
 Available in all editions of SQL Server (from the Express!)
 Available in SQL Azure
 ANSI 2011 compliant
 Provide native support for temporal queries
 Transparent to existing applications (if needed)
 Integrated with existing features (eg: Partitioning, Hekaton)
 Integrated with new features (eg: Stretch Database)

6. TEMPORAL QUERIES
 SQL Server 2016 supports
 AS OF <date_time>
 FROM <start_date_time>TO <end_date_time>
 BETWEEN <start_date_time> AND <end_date_time>
 CONTAINED IN (<start_date_time> , <end_date_time>)
 ALL
http://www.ics.uci.edu/~alspaugh/cls/shr/allen.html

7. TEMPORALTABLES
 Some limitations compared to “classic” tables
 NoTRUNCATETABLE support
 INSTEADOF triggers not supported
 Temporal tables *can* be ALTERed
 A few limitations:
 Cannot add a computed columns
 Cannot add an Identity column
 Versioning can be turned on/off as we wish
 There is *no* automatic cleanup of versioning
 Stretch Database offer “a sort of” automatic archival (but still no cleaning!)
 Tips: https://msdn.microsoft.com/library/mt637341.aspx

8. DEMO!
Let’s see some live action!

9. TEMPORALTABLES
 Some limitations compared to “classic” tables
 NoTRUNCATETABLE support
 INSTEADOF triggers not supported
 Temporal tables *can* be ALTERed
 A few limitations:
 Cannot add a computed columns
 Cannot add an Identity column
 Versioning can be turned on/off as we wish
 There is *no* automatic cleanup of versioning
 Stretch Database offer “a sort of” automatic archival (but still no cleaning!)
 Tips: https://msdn.microsoft.com/library/mt637341.aspx

10. TEMPORALTABLES
 Temporal queries with other operators than “AS OF” can be tricky
 Especially if you’re joining temporal tables
 Rows and not unpacked and then packed back!
 Hugh Darwen http://www.dcs.warwick.ac.uk/~hugh/

11. DEMO!
Tricky stuff….

12. ADDITIONAL READS
 First Look at System-VersionedTemporalTables
 http://sqlmag.com/sql-server/first-look-system-versioned-temporal-tables-part-1-
creating-tables-and-modifying-data
 http://sqlmag.com/sql-server/first-look-system-versioned-temporal-tables-part-2-
querying-data-and-optimization-conside
 Temporal data (as a general topic)
 https://www.amazon.com/Time-Relational-Theory-Second-
Management/dp/0128006315
 https://www.pluralsight.com/courses/working-with-temporal-data-sql-server

13. VOTE ON CONNECT
 Temporal support is good but can be improved! Help telling Microsoft you what
more:
 Add SQL Server Engine Support for Interval Queries (Intersection/Overlap and other
Allen’s interval algebra relations)
 https://connect.microsoft.com/SQLServer/Feedback/Details/780746
 TemporalTables: Connect Item Round Up
 http://sqlblog.com/blogs/adam_machanic/archive/2016/10/04/temporal-tables-connect-item-
round-up.aspx

14. THANKS!