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Category: Temporal Tables

More On Temporal Tables

Newly-minted Canadian citizen Randolph West’s latest article is on modifying temporal tables:

Last week I demonstrated how temporal tables in SQL Server 2016 work. If you have implemented a history table—populating it with triggers or stored procedures—it works the same way.

This week, we are going to look at how to modify a temporal table that already has data in the history table.

If you’re using temporal tables for auditing, it’s important to know that yes, data can be modified.

Reza Rad also has a recent blog post on temporal tables:

Temporal tables are new type of database tables introduced in SQL Server 2016, these tables are system-versioned and keep history of changes (insert, delete, update) of everything happened on data rows. Retrieving change log from these tables are easy. These tables can simply tell you what was the data at specific point of the time in the table. These tables works with datetime2 columns to keep FROM DATE and TO DATE information of each change. This means these tables can be used for implementing changes in dimensions, yes you know what it called; Slowly Changing Dimension!

Slowly-changing dimensions in an OLTP scenario was the first use I could think of for temporal tables, so I’m glad Reza put this article together.

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More On Temporal Tables

Randolph West has another nice post on temporal tables, in which he lets the cat out of the bag:

Look at the log records. They are identical to before. In fact, because a trigger is called in the same implicit transaction as the UPDATE statement, we didn’t even need to wrap the INSERT statement in a transaction.

What have we learned?

Temporal tables are doing exactly what an update or delete trigger (or stored procedure) would do, based on what we saw in the log records.

This is an in-depth look at what, exactly, is happening when temporal tables get updated.

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