ApplicationInsights looks at individual instances when collecting data. An instance is defined as a nsf/ntf container living on a server having a replica ID. A Domino application or 'database' is determined by a unique replica id and can be represented by more than one instance (replicas).
Why are we collecting info about different instances instead of just one?
By looking at the instances we can give you more granular and detailed information about the application. Like on which servers it exists, which instances are being used by which users and if there are differences in design between replicas (for instance when replication is broken).
It also allows us to indicate differences in design between application instances and problems with replication, the design task, design inheritance settings and duplicate templates that could cause differences in design.
Database / application:
If in this documentation the term 'database' or in some cases 'application'* is used, it represents a unique database identified as a file with extension .NSF or .NTF and all its analyzed** instances (replicas) on other servers. Also, if in this document the term 'application' is used in reference to analyzed databases, it refers to databases of both type Mail-In databases and Applications.
If the term instance is used, a single replica of that database is meant. Note that more than one instance with the same replica ID may exist on any given server.
* The term 'application' is also used to indicate a category type of databases as defined in the topic Definitions.
** As panagenda ApplicationsInsights only has insights into the instances on servers it is analyzing it is important to ensure all servers are included in your discovery set. For details about this please refer to the technical documentation.