A versioned database is an ArcSDE service that has been configured to support multiple versioned views of the database. There is a single versioned database in an ArcSDE service. The versioned database consists of a collection of tables that participate in the versioned database. Not all tables in a DBMS service need to be (or even should be) part of the versioned database. The versioned database defines a single schema. If the schema of the database is changed, it is changed for all versions of that database.

A versioned database will typically contain a number of versions, in addition to the DEFAULT version, that might represent a work order, a design alternative, a disconnected editing session, a historical snapshot, and so on. The VERSIONS table contains a descriptive list of these versions with each version identified by a unique name and ID (IDs are automatically generated by ArcSDE). In addition, each version has an owner, description, parent version, associated database state, and level of user access.

The three levels of version access are:

• Private—Only the owner can view and edit
• Protected—All users can view, but only the owner can edit
• Public—All users can view and edit

When the VERSIONS table is first created, the details of the DEFAULT version are automatically recorded in this table. The sde administrator owns the DEFAULT version, and the initial ID of the corresponding database state will be set to 0. The description string will read Instance Default Version and, because the DEFAULT version has been granted PUBLIC access, any user can modify it. To support general connections to the geodatabase, the level of access to the DEFAULT version must remain either Public or Protected; if the access level were set to Private, only the sde administrator could connect to the database.