DS_TOTAL_MEMORY

onconfig.std value

On UNIX: None
On Windows NT: 4,096

if not present

For Extended Parallel Server:
If SHMTOTAL=0, DS_TOTAL_MEMORY defaults to (NUMCPUVPS * 4 * 128). If SHMTOTAL is greater than 0, the value is SHMTOTAL minus all memory other than decision-support memory, which includes the resident memory segment, memory reserved for buffer cache, and memory reserved for user connections in various protocols, which is specified by the third argument of the NETTYPE parameter. (The default value for this argument to NETTYPE is 50 connections.)

units

Kilobytes

range of values

The maximum value is 2 gigabytes on 32-bit platforms and 4 gigabytes on 64-bit platforms.

The minimum value is NUMCPUVPS * 4 * 128.

utilities

onutil

refer to

The following materials:

• Your IBM Informix: Performance Guide for the algorithms
• Derive a Minimum for Decision-Support Memory

DS_TOTAL_MEMORY specifies the amount of memory available for PDQ queries. It should be smaller than the computer physical memory, minus fixed overhead such as operating-system size and buffer-pool size.

Do not confuse DS_TOTAL_MEMORY with the configuration parameter SHMTOTAL. For OLTP applications, set DS_TOTAL_MEMORY to between 20 and 50 percent of the value of SHMTOTAL in kilobytes. For applications that involve large decision-support queries, increase the value of DS_TOTAL_MEMORY to between 50 and 80 percent of SHMTOTAL. If you use your database server for decision-support queries exclusively, set this parameter to 90 percent of SHMTOTAL.

For DSS-only applications that do not need to balance resources against OLTP applications, you can allocate all of the virtual portion to your decision-support queries. Set the DS_TOTAL_MEMORY configuration parameter to any value not greater than the quantity (SHMVIRTSIZE - 10 megabytes).