What is the purpose of the 'tracking.history' MongoDB database?

Question

Sitecore XP version 8.0, 8.1 and 8.2 comes with following MongoDB databases:

• analytics
• tracking.live
• tracking.history
• tracking.contact

What is the purpose of the tracking.history database in MongoDB?

Answer 1

Tracking History

The tracking.history database is used by one entity only:

• History Processing Pool (defined in the Sitecore.Analytics.Processing.Aggregation.ProcessingPools.config file).

History Processing Pool

It works with the ProcessingPool collection that is defined in the tracking.history database. During aggregation of a history data (rebuild of the reporting SQL database aka RDB) this pool is populated with the work items.

The History Processing Pool is referenced by two entities:

• History Task Manager (defined in the Sitecore.Analytics.Processing.Aggregation.ProcessingPools.config file)
• History Interaction Aggregation Context (defined in the Sitecore.Analytics.Processing.Aggregation.config file)

History Task Manager

It manages all tasks related to aggregation of history data, and is used by various agents that are responsible for history data aggregation (rebuild of the reporting database).

History Interaction Aggregation context

It is referenced by the Interaction Work Dispatcher (defined in the Sitecore.Analytics.Processing.Aggregation.Services.config file), where the dispatcher is used by the Aggregation Cleanup and Aggregation Recovery agents (both defined in the Sitecore.Analytics.Processing.Aggregation.Services.config file).

Additionally, both the History Interaction Aggregation Context and History Task Manager are used by the History Worker (defined in the Sitecore.Analytics.Processing.Aggregation.Services.config file). The worker runs by the Processing / Aggregation role. It gets work items from the history processing pool using the History Task Manager. Each work item is processed by calling the analytics.aggregation/interactions pipeline.