Sitecore xConnect and xDB | Sitecore CMS Development Company

Sitecore’s Experience Database (xDB) is mainly used to store analytics data and to track how people interact with your site.

xDB was introduced in Sitecore 7.5.
From Sitecore 7.5 to Sitecore 8.2 its used MongoDB to store analytics data.
From Sitecore 9 the analytics data were stored in SQL Server and we can store data in MongoDB as an option from Sitecore 9.0 Update 2 and later.
xDB will show you the values for visits and track the people accordingly.
We need to enable the xDB from the config. The config Path is “Your Website > App_Config > Sitecore > Marketing.XDB > Sitecore.Xdb.config”. In that file we need to set Xdb.Enabled value as true.
xConnect is the service between the xDB collection Database and the xDB Index. It helps to read and write the interactions.
Set of APIs and services to integrate data from third-party systems to Sitecore Experience Database (xDB).
Stores all contact and interaction data, Campaign, including identifiers and facets.
The xDB Reference Data database contains marketing reference content for all xDB data, such as definitions and taxonomies.

The xDB Reference Data database is referenced by the following roles:

xDB Processing
Reference Data service
Marketing Automation Engine
Marketing Automation Operations service

The marketers can see the xDB collection data of known contacts, and the values for their visits, and they can track the customer from Experience Profile.

As you can imagine, the xDB collection database can possibly contain large amounts of visitor information.

Sitecore Shared databases are used to store contacts, interactions, and device profiles.

The shard map manager database is to manage the multiple shard databases.

Experience data is shared in the following way:

Contact and interaction data is shared by contact ID.
The identifiers index is sharded by identifier.
Device profiles are sharded by device profile ID.