Kbase P82933: -Bt may result in very little performance gain
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
12/15/2008 |
|
Status: Verified
SYMPTOM(s):
-Bt may result in very little performance gain
FACT(s) (Environment):
All Supported Operating Systems
Progress 9.x
OpenEdge 10.x
CAUSE:
When using -Bt, Progress works as much as possible in the -Bt buffer pool until it is full, then it starts to involve the dbi temp file on disk to swap that pool. With a high value of -Bt, it can result in not even touching the dbi file at all and work only in memory.
However, on modern systems (lot of memory available, fast disks), in case of intensive usage of temp-tables, using a high value for -Bt (without involving memory swap) may result in a very little performance gain compared to not using it at all. This is due to the facts that:
1) Without -Bt the Operating System caches the dbi file in such a way that everything really happens in memory anyway.
2) Flushing the -Bt pool to the dbi is done regularly and smoothly without introducing a bottleneck of the system. Note that long 4GL jobs with intensive usage of temp-tables usually lead to a bottleneck on CPU resource, not on Disk IO.
-Bt might really help when the OS File System cache is limited or when there can be a disk IO bottleneck, such as when many AppServer Agents running on multiple CPU's share the same disk for temp files.
See Progress Solution 20339 How Parameter -Bt works With Temp-Tables
FIX:
Test the usage of -Bt. If no gain then just do not use it.