The image shows a high level architecture diagram for Oracle Globally Distributed Database. The diagram is divided vertically into three sections: App Tier on top, Routing Tier in the center, and Data Tier on the bottom.

The Data Tier section on the bottom contains database icons representing the shards. there are 2 rows of 4 shards.

The Routing Tier section in the middle contains 2 icons: the icon on the left is labeled Global Data Service (GDS) Shard Director/GSM Listener, and the icon on the lower right is labeled Catalog Database. These icons are connected by a dotted line.

The App Tier section on top shows a Sharding Key (Customer 123) pointing at a Connection Pool. The Connection Pool in turn points to the top row of 4 shards in the Data Tier, passing through the Global Data Services icon in the Routing Tier.