The Postgres Pro Shardman software comprises these main components: PostgreSQL core with additional features, shardman extension, management services and utilities. This section considers Postgres Pro Shardman cluster as a group of PostgreSQL instances or shards. Each shard may also have several standby nodes and to emphasize this the term replication group is used. The support for highly available configurations is currently done on the level of tools and services and will be covered in the Management section.