Re: Why long transaction cannot rollback?????

In article <33446552.1397@xnet.com>, "William J. Mitlyng" <wmitlyng@xnet.com> wrote: >I am not sure whether this applies to your version of Informix; however, >I was told in a performance and tuning class that the system will >examine the logical logs after passing the high water mark and examine >the processes active in the current logical log. If one has five logical >logs and there happens to be one unfinished transaction in the first >logical log and the mark is passed in the third logical log, the >transactions in the third logcal log are targeted for rollback. >The transaction in the first logical log will continue to remain active >without being rolled back. This condition will fill your logical logs if >the transaction of the first logical log continues to produce >modifications. The only way around this is to be alerted when LTXHWM is >crossed and closley examine the logical logs to see if a process must be >terminated. > >If I am in error please email me. I would not want to plod on >erroneously in this area. > When LTXHWM is reached, Informix STARTS LOOKING for the long transaction (in your example, the trx. which started in Log 1). After it is identified, it is rolled back. If before the 'long trx' is found, LTXEHWM is reached, Informix puts all users on 'hold' (except those in 'critical' phases) and concentrates on identifying and rolling back the long transaction. Transactions, other than the 'long' trx are never aborted. Of course, the system could 'lock' is log space to roll back the 'long' trx. is not sufficient. ----------------------- Rudy Fernandes GIC, Kuwait OL 7.20UC4, 4GL 6.04UC1 -----------------------