Reasons for rebuilding the reporting database

Current version: 10.2

When you rebuild the reporting database, you reprocess the interactions that have already been aggregated into the reporting database.

The rebuilding process merges historical data from earlier versions of Sitecore with live xDB data, making all the data available to Sitecore reporting applications. One of the main reasons for rebuilding the reporting database is as the final step of the conversion process.

Warning

To ensure that the reporting database contains the latest data changes, you need to rebuild it from time to time. When you rebuild the reporting database, you overwrite its contents. To avoid overwriting data, use a clean copy of the reporting database as the target database every time you perform a rebuild.

Rebuild the reporting database if:

You have made changes to the collection database - rebuild is necessary to reflect the changes in reports that use older data. For example, if you have changed the channel associated with one of your referring sites.
You have reclassified reporting data – In Experience Analytics and other Sitecore reporting applications it is possible to reclassify data that has already been processed by the aggregation layer. For example, if you have reclassified a search key word or channel, aggregated report data is not automatically updated. This can cause the reporting database to become out of sync with the collection database.
Your databases are out of sync – if the reporting database has been lost or has become out of sync with the collection database, for example, due to a disaster or if contacts have been merged. The accuracy of the reporting database can decrease over time as more contacts are merged and more interactions are imported. How often you need to rebuild the reporting database depends on your system architecture and the amount of merges and imports you need to process.
You removed contacts using the xConnect client API.
You used the xDB Data Purge tool.

After rebuilding the reporting database, some reports based on contact facets may become inaccurate. This is because contact facets can change over time and, as a result, Experience Analytic dimensions that use filter rules based on contact facets will not provide accurate data. This means, for example:

If the filter is based on contact facets that do not change over time (such as email addresses), the report will remain accurate after a rebuild.
If the filter is based on contact facets that change over time (such as Contact Behaviour Profile Pattern matches), the report will be inaccurate after a rebuild.