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 want to have the result that was returned at 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 in such a simple what that anyone, even on *current* applications, can benefit from it, simplifying solution architecture and saving time (and money) on maintenance an reporting. In this session we’ll see how the feature work on SQL Server 2016 and Azure SQL v12 and also what will be available in the vNext version of SQL Server.

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

2. DAVIDE MAURI
 Microsoft Data Platform MVP since 2006
 Works with SQL Server from 6.5, on BI from 2003
 Specialized in Data SolutionArchitecture, Database Design, PerformanceTuning, High-
Performance DataWarehousing, BI, Big Data
 Very strong developer background
 Loves community!
 President of UGISS (Italian SQL Server UG) for 11Years, AppDevVG Leader since 2017
 Regular Speaker @ SQL Server events
 Director SW & Cloud @ Sensoria: http://www.sensoriafitness.com/
 E-mail: info@davidemauri.it -Twitter: @mauridb
 Blog: http://sqlblog.com/blogs/davide_mauri/default.aspx

3. LOVE AT FIRST SIGHT!
 TemporalTables

4. THINGSTO KEEP IN MIND
 Stored interval is half-open: [valid_from, valid_to)
 >= valid_fromAND < valid_to
 Stored interval is in UTC

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, ColumnStore)
 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
 https://docs.microsoft.com/en-us/sql/relational-databases/tables/temporal-tables
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

8. TEMPORALTABLES
 SQL 2016: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
 SQL vNext – Azure SQL:There *is* an automatic cleanup process of versioning
 https://docs.microsoft.com/en-us/azure/sql-database/sql-database-temporal-tables-
retention-policy

9. DEMO!
Let’s see some live action!

10. TEMPORALTABLES
 Temporal queries with other operators than “AS OF” can be tricky
 Especially if you’re joining temporal tables
 Rows are 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
 Usage Scenarios
 https://docs.microsoft.com/en-us/sql/relational-databases/tables/temporal-table-usage-
scenarios
 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!