Sybase IQ allocates memory for various purposes from a single memory pool, called server memory. Server memory includes all of the memory allocated for managing buffers, transactions, databases, and servers.
At the operating system level, Sybase IQ server memory consists of heap memory. For the most part, you do not need to be concerned with whether memory used by Sybase IQ is heap memory or shared memory. All memory allocation is handled automatically. However, you may need to make sure that your operating system kernel is correctly configured to use shared memory before you run Sybase IQ. See the Sybase IQ Installation and Configuration Guide for your platform for details.
Each server in the multiplex can be on its own host or share a host with other servers. Two or more servers on the same system consume no more CPU time than would a single combined server handling the same workload, but separate servers might need more physical memory than a single combined server, because the memory used by each server is not shared by any other server.
To avoid overallocating the physical memory on the machine, you can set the LOAD_MEMORY_MB database option for operations where loads occur. In addition to LOAD operations, this option affects INSERT, UPDATE, SYNCHRONIZE and DELETE operations. The LOAD_MEMORY_MB option sets an upper bound (in MB) on the amount of heap memory subsequent loads can use. For information on loads and buffer cache use, see “Memory requirements for loads”. For details of the LOAD_MEMORY_MB option, see Chapter 2, “Database Options,” in the Sybase IQ Reference Manual.
WARNING! Killing processes on UNIX systems may result in semaphores or shared memory being left behind instead of being cleaned up automatically. The correct way to shut down a Sybase IQ server on UNIX is the stop_asiq utility, described in “Stopping the database server” in Chapter 2, “Running Sybase IQ,” Sybase IQ System Administration Guide. For information on using the ipcs and ipcrm to clean up after an abnormal exit, see Chapter 1, “Troubleshooting Hints,” in Sybase IQ Troubleshooting and Recovery Guide.
