Kbase P145389: The _BiLogTtotReads VST field is not increasing as expected during a transaction rollback.
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
08/03/2010 |
|
Status: Verified
SYMPTOM(s):
The _BiLogTtotReads VST field is not increasing as expected during a transaction rollback
The _BiLogTtotReads VST field increases for activities other than transaction rollbacks
Attempts to use the _BiLogTtotReads increasing count to warn of increasing transaction rollbacks is not accurate
FACT(s) (Environment):
The _BiLog-TotReads field is from the VST table _ActBILog
All Supported Operating Systems
OpenEdge 10.1B03 Service Pack
CAUSE:
Although _BiLog-TotReads is defined as: Number of BI blocks read from the BI file to undo transactions, it does increase for other types of activity and may have no increase or just a slight increase during a transaction rollback.
FIX:
The _BiLog-TotReads count can increase for activity other than a transaction rollback , such as a few BI blocks are also read when new clusters are opened, when a cluster is closed, and when old clusters are reformatted.
It is possible that a small transaction can be rolled back without reading bi blocks from disk /if/ there are enough unwritten bi buffers in memory and the transaction is entirely contained within them.
A transaction that did not make any changes will have its transaction begin note buffered (never written) and a rollback can be done without reading any blocks.
Although the _BiLog-TotReads field is defined in this manner, it is not the sole activity responsible for an increase in this counter and should not be expected to accurately reflect the transaction rollback activity for a database
Note:
Use the VST table/field that specifically deals with transactions rolled back to monitor rollbacks. The field _Other-Undo (Number of transactions rolled back) of the VST table _ActOther can be used to monitor the number of transaction rollbacks.