Active GB includes all the storage and compute your data requires, measured as the total number of uncompressed bytes in one single copy of your data. One rough approximation of this size is the total number of bytes returned by the "SELECT * FROM my_collection" query. In addition to storing your active data, Rockset automatically builds indexes to speed up queries, and maintains online and offline replicas for high availability and durability. The associated compute required for ingesting and processing queries on your active data is automatically provisioned and included in your plan.
Rockset charges based solely on active GB; the additional storage requirements of indexes and replicas are not counted towards your usage. In contrast, other database systems must be provisioned with enough storage to account for indexes, backups, replicas, and other internal operations (such as periodically compacting the database to improve performance), and often require additional compute for tools that transform and load data.