Row Inserted and Updated Time in Fact Table

Question

I see there is an importance in having a row inserted and a row last updated fields in a fact table. But I could not find any standard data warehouse or a reference which says that this is a good thing to do. I am uncertain whether this is because it is a bad practice; if so why should it be so? If it is because of the data size, I see it is only 8bytes for a full date field.

Any help is greatly appreciated!!!

Answer 1

There's nothing talking about whether it's a good or bad practice because we include creation time and updated time only if we need them or ever will need them.

It's a "good thing to do" if you need to access those columns and a "bad thing to do" if your table will never require those columns.

Answer 2

The inclusion of insert and update timestamps in your data warehouse tables allow you to be able to report from the perspective of as was and/or as is with regards to the data warehouse. These timestamps would be in addition to any timestamps that may be captured from the source.

They also make troubleshooting easier and in a worse case scenario the ability to back out a set of data from a specific run of an ETL process.

At a previous client, the data model we implemented included upwards of 6 different timestamps to provide slowly changing history, as is/ as was reporting, and source related time stamps. It made for very flexible reporting but also increased the learning curve of how to get exactly what you wanted from the table(s).