Hello everyone.
Following one of the recent threads I read about BTscanner and how it works.
Then I checked its output and found out potential place for optimization.
Or maybe I'm just misinterpreting the output.
The problem is that "onstat -C range" reports many 100% (or close) savings
if range scanning is used. A part of the output follows at the end of the
post.
My question is: based on the output, how do I calculate range threshold that
should be set (it's currently disabled) to improve index performance?
Thanks everyone.

P.S. I recently restarted the instance, plus now it's period of very low
user activity so the numbers aren't representative, but still I'm curious
about the formula for range threshold.

IBM Informix Dynamic Server Version 9.40.UC5W2 -- On-Line -- Up 2 days
22:52:42 -- 1917952 Kbytes

Btree Cleaner Info

Cleaning Range Statistics
=========================
Partnum Key Low High Size Saving
0x00100002 1 1 1 4 100.0 %
0x00200005 1 6214 6375 8016 98.0 %
0x00200005 2 743 6440 8016 28.9 %
0x00200007 1 92 92 2508 100.0 %
0x00200009 1 37 61 1008 97.6 %
0x00200009 2 66 66 1008 100.0 %
0x0020000d 1 14 14 1008 100.0 %
0x0020000d 2 10 10 1008 100.0 %
0x00200011 2 569 569 10064 100.0 %
0x00200011 3 93 741 10064 93.6 %
0x00200014 1 1802 1927 10032 98.8 %
0x00200014 2 2307 8880 10032 34.5 %
0x0020001a 1 5 5 508 100.0 %
0x0020002d 1 50 251 508 60.4 %
0x0020002d 2 20 131 508 78.1 %
0x0020003a 1 540 1016 1386 65.7 %
0x00200048 1 1 1 18 100.0 %
0x00200049 1 1 1 28 100.0 %
0x0020004f 1 4 103 3906 97.5 %
0x00200050 1 5 24 1375 98.6 %
0x00200052 1 7 61 2875 98.1 %
0x00200054 1 26 26 36 100.0 %
0x00200055 1 3 6 8 62.5 %
0x0020005c 1 2 4 129 98.4 %
0x0020005d 1 1 1 70 100.0 %
0x0020006f 1 2 6 20 80.0 %
0x00200070 1 1 1 14 100.0 %
0x00200072 1 2 3 6 83.3 %
0x00200073 1 2 9 36 80.6 %
0x00200074 1 3 6 20 85.0 %
0x00200076 1 3 4 25 96.0 %
0x002000d8 1 7 7 277 100.0 %
0x002000dc 1 2 2 120 100.0 %
0x002000dd 1 2 3 156 99.4 %
0x002000de 1 2 3 132 99.2 %
0x002000e0 1 8 8 247 100.0 %
0x002000e2 1 6 6 296 100.0 %
0x002000e4 1 1 1 129 100.0 %
0x002000e5 1 3 3 140 100.0 %
0x002000e7 1 1 1 118 100.0 %
0x002000e8 1 6 6 294 100.0 %
0x002000ed 1 1 1 140 100.0 %
....