DS_TOTAL_MEMORY

onconfig.std value

On UNIX: None
On Windows: 4,096

if not present

If SHMTOTAL=0 and DS_MAX_QUERIES is set, DS_TOTAL_MEMORY = DS_MAX_QUERIES * 128.

If SHMTOTAL=0 and DS_MAX_QUERIES is not set, DS_TOTAL_MEMORY = num_cpu_vps * 2 * 128.

units

Kilobytes

range of values

If DS_MAX_QUERY is set, the minimum value is DS_MAX_QUERY * 128.

If DS_MAX_QUERY is not set, the minimum value is num_cpu_vps * 2 * 128.

Maximum value for 32-bit platform:
2 gigabytes
Maximum value for 64-bit platform:
4 gigabytes

utilities

onmode -M (See page Change Decision-Support Parameters.)
onstat -g mgm (See The onstat -g mgm Option.)

refer to

The following material:

• Your IBM Informix Performance Guide for the algorithms
• SHMTOTAL
• SHMVIRTSIZE
• Specifying the Number of CPU VPs
• The maximum memory available on your platform, in the machine notes

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 parameters SHMTOTAL and SHMVIRTSIZE. SHMTOTAL specifies all the memory for the database server (total of the resident, virtual, and message portions of memory). SHMVIRTSIZE specifies the size of the virtual portion. DS_TOTAL_MEMORY is part of SHMVIRTSIZE.

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 (DSS) queries, increase the value of DS_TOTAL_MEMORY to between 50 and 80 percent of SHMTOTAL. If you use your database server for DSS queries exclusively, set this parameter to 90 and 100 percent of SHMTOTAL.

Set the DS_TOTAL_MEMORY configuration parameter to any value not greater than the quantity (SHMVIRTSIZE - 10 megabytes).