A subset of the data and associated metadata stored in an Eon Mode database. Shards are how Vertica divides the work of processing queries, data loads, and data maintenance between the nodes in a subcluster. Nodes subscribe to one or more shards. When processing a query, each node is responsible for processing the data in the shard or shards to which it subscribes.
You set the number of shards for the database during the database creation process. The number of shards cannot be changed after creathing the database.
Shards have a single primary subscriber in the database cluster. The primary subscriber node maintains the data in the shard by running Tuple Mover processes on it.