The number of databases is unlimited. The limiting factor is the available memory in the cluster, and the number of shards in the subscription. A shard is any provisioned database instance (master copy, slave copy or a database instance that is part of a clustered database).
Note the impact of the specific database configuration on the number of shards it consumes. For example:
- Enabling database replication, without enabling database clustering, creates two shards: a master shard and a slave shard.
- Enabling database clustering creates as many database shards as you configure.
- Enabling both database replication and database clustering creates double the number of database shards you configure.