On the upper left of the illustration is a circle with "https" inside of it, and an arrow. Attached to the circle is a rectangle that contains "Customer 123." To the right of this icon are the words "Sharding Key e.g., customerID." Underneath this box is a box labeled "Application Servers." The Application Servers box has five arrows pointing down to five cylinders, labeled "Shards." A callout labels these shards as "Sharded Database (SDB)." The left arrow is labeled "Shard Directors." The right arrow is labeled "Shard Catalog."