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SMI Query Series - Shared Memory Segments

SMI Query Series - Shared Memory Segments

The sysmaster interface (SMI) presents a comfortable way to extract information about various parts of your running IDS instance. This information can be used for:

  • ad hoc analysis of performance problems
  • determining the status of several IDS sub components
  • monitoring replication metrics
  • sampling data for capacity planning purposes
  • tracking system usage of individual sessions
  • and many more...

The below SMI query is the third one of a new SMI query series at The Informix Zone. The queries show you how to extract valuable information from the sysmaster database.

smi_mem_seg.sql

The purpose of this SMI query is to display the allocated, used and free number of megabytes for the individual IDS shared memory segment areas:

  • Resident Segment
  • Virtual Segment(s)
  • Message Segment

The corresponding onstat command is: onstat -g seg

SELECT DECODE
       (
         seg_class,
         1, "Resident",
         2, "Virtual",
         3, "Message"
       ),
       COUNT(*) count_seg,
       (SUM(seg_blkused + seg_blkfree)*4/1024) mb_total,
       (SUM(seg_blkused)*4/1024) mb_used,
       (SUM(seg_blkfree)*4/1024) mb_free
FROM  syssegments
GROUP BY 1
ORDER BY 1;
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