How a Client Attaches to the Communications Portion

Client-application processes that communicate with the database server through shared memory (nettype ipcshm) attach transparently to the communications portion of shared memory. System-library functions that are automatically compiled into the application enable it to attach to the communications portion of shared memory. For information on specifying a shared-memory connection, see Client/Server Communications, and Network Virtual Processors.

If the INFORMIXSHMBASE environment variable is not set, the client application attaches to the communications portion at an address that is platform specific. If the client application attaches to other shared-memory segments (not database server shared memory), the user can set the INFORMIXSHMBASE environment variable to specify the address at which to attach the database server shared-memory communications segments. When you specify the address at which to address the shared-memory communications segments, you can prevent the database server from colliding with the other shared-memory segments that your application uses. For information on how to set the INFORMIXSHMBASE environment variable, refer to the IBM Informix: Guide to SQL Reference.