CommonDB is a database designated to hold all of the common information to the partitions to avoid duplicated sets of data, that would otherwise be stored on each partition database. The use of common database does not only saves physical space, but also makes updating information much easier and more efficient. Updates are done only at commonDB and not at every partitionDB.
The CommonDB is a useful integral part of our platform. It is valuable for both SaaS database design, as well as for a more straightforward databases. Therefore, you are encouraged to use it.
Common access active
Common access active is a gate attribute that defines the level of access between the partition databases and the CommonDB.
Common access active set to true
Under this setting the system keeps a linked server to and from each childDB to the CommonDB. This means that foreign key relations are permitted from any ChildDB to the CommonDB and all of the triggers involving foreign keys are kept (checking upon deletion etc.)
This setting keeps the integrity of the database since it validates all updates against the related databases, and prevents updates that might break the database coherency.
However, this property technically allows any partition to reach to other partitions by queries passing the CommonDB. This situation may not meet your security requirements. Therefore, based on your needs you will have to decide if you can take advantage of the “common access active” feature.
Common access active set to false
Under this setting each ChildDB has a linked server to the CommonDB, but not the other way around. This means that foreign keys to the CommonDB are not supported, but obviously queries involving both a ChildDB and the CommonDB are not a problem, all type of commands that you are accustomed to, are supported.
To learn more about the common access active property click here.