8.1.2 Fabric Concepts

This section describes some of the concepts used in Fabric.

A high-availability group, or simply group, is a collection of servers. It is used to associate the servers in a set. This association may be a set of replication-enabled servers, the servers participating in a sharding solution, and so forth.

A group identifier is the name we give a group or members of the group. A group identifier is a name that matches the regular expression [a-zA-Z0-9_-]+. Examples of legal identifiers are my_group, employees, and shard1.

A global group stores all updates that must be propogated to all shards that are part of a sharding scheme.

A node or fabric node is an instance of the Fabric system running on a server. To use the features of Fabric, at least one Fabric node must be running.

Sharding refers to the Fabric feature that permits the distribution of data across several servers. There are many uses of sharding but the most effective use of sharding enables distributing the work of writing across several servers for improved write speeds.

A shard is a horizontal partition or segment of data in a table.

Primary refers to a member of a group that is designated as master in the sense that it can accept read-write transactions.

Secondary refers to a member of a group that can be a candidate to replace the master during switchover or failover and that can accept read-only transactions.