Server Groups Overview

A server group specifies the SQLFire members that will host data for a table. You use a server group to logically group SQLFire data stores for managing a table's data.

Any number of SQLFire members that host data can participate in one or more server groups. You specify named server groups when you start a SQLFire data store.

A SQLFire member that is booted with host-data=false is an accessor and does not host table data, even if you specify one or more server groups. However, peer clients that host data can also participate in server groups.

By default, all servers that host data are added to the "default" server group.

Different logical database schema are often managed in different server groups. For example, an order management system might manage all customers and their orders in an "Orders" schema deployed to one server group. The same system might manage shipping and logistics data in a different server group. A single peer or server can participate in multiple server groups, typically as a way to colocate related data or to control the number of redundant copies in replicated tables.

With support for dynamic group membership, the number of processes hosting data for a server group can change dynamically. However, this dynamic aspect of server group membership is abstracted away from the application developer, who can look at a server group as a single logical server.

Server groups only determine those peers and servers where a table's data is being managed. Tables are always accessible for any peer member of the distributed system, and from thin clients that connect to a single server.

When you invoke server side procedures, you can parallelize the execution of the procedure on all members in the server group. These data-aware procedures also execute on any peer clients that belong to the server groups.

Without associating tables to specific member IP addresses, the capacity of a server group can be dynamically increased or decreased without any impact to existing servers or client applications. SQLFire can automatically rebalance the tables in the server group to the newly added members.