About the Components of Globally Distributed Autonomous Database

To gain a greater understanding of the Globally Distributed Autonomous Database concepts, familiarize yourself with the following terminology.

• Catalog - an Oracle Database that supports automated shard deployment, centralized management of Globally Distributed Autonomous Database, and multi-shard queries.

  A Catalog serves following purposes:

  • Serves as an administrative server for the entire Globally Distributed Autonomous Database

  • Stores a gold copy of the database schema

  • Manages multi-shard queries with a multi-shard query coordinator

  • Stores a gold copy of duplicated table data

• Shard - Globally Distributed Autonomous Database is a collection of shards.

  Each shard in Globally Distributed Autonomous Database is an independent Oracle Database instance that hosts subset of Globally Distributed Autonomous Database data. Shared storage is not required across the shards.

  Shards can all be placed in one region or can be placed in different regions.

  Shards are replicated for high availability and disaster recovery with Oracle Data Guard. For high availability, Data Guard standby shards can be placed in the same region where the primary shards are placed. For disaster recovery, the standby shards can be located in another region.

• Shardspace - A shardspace is a shard that stores data corresponding to a range or list of key values in a user-managed data distribution configuration. A shardspace consists of a shard and its replica.

• Shard director - A network listener that enable high performance connection routing based on a sharding key. In addition, a shard director is a set of processes known collectively as a Global Service Manager (GSM) that acts as a regional listener for clients that connect to Globally Distributed Autonomous Database.

  The shard director maintains a current topology map of Globally Distributed Autonomous Database. Based on the sharding key passed during a connection request, the director routes the connections to the appropriate shard.

• Global service - A database service that is used to access data in Globally Distributed Autonomous Database.

  A global service is an extension to the notion of the traditional database service. All of the properties of traditional database services are supported for global services.

For more in depth information about Globally Distributed Autonomous Database components and schema objects see Oracle Sharding Architecture and Concepts in Using Oracle Sharding.