Using Multiple Connection Types

A single instance of the database server can provide more than one type of connection. Figure 19 illustrates such a configuration. The database server is on host river. Client A connects to the database server with a shared-memory connection because shared memory is fast. Client B must use a network connection because the client and server are on different computers.

When you want the database server to accept more than one type of connection, you must take the following actions:

• Put DBSERVERNAME and DBSERVERALIASES entries in the ONCONFIG configuration file.
• Put an entry in the sqlhosts file for each database server/connection type pair.

For the configuration in Figure 19, the database server has two dbservernames: river_net and river_shm. The ONCONFIG configuration file includes the following entries:

DBSERVERNAME                  river_net
DBSERVERALIASES                  river_shm

Figure 19. A UNIX Configuration That Uses Multiple Connection Types

The dbservername used by a client application determines the type of connection that is used. Client A uses the following statement to connect to the fully parallel-processing database server:

CONNECT TO '@river_shm'

In the sqlhosts file, the nettype associated with the name river_shm specifies a shared-memory connection, so this connection is a shared-memory connection.

Client B uses the following statement to connect to the database server:

CONNECT TO '@river_net'

In the sqlhosts file, the nettype value associated with river_net specifies a network (TCP/IP) connection, so client B uses a network connection.