John Adamski posted a question to the IIUG SIGs
about how to identify a session that caused the long transaction that eventually put his system in a Blocked:LONGTX state. A few of us came back with some responses, but it wasn’t until John Miller III from IBM and Informix Fun Facts
replied with “finding the session that caused your long transaction isn’t very useful, you need to prevent this situation from happening with the LTXHWM and LTXEHWM ONCONFIG parameters” that I realized these config parameters are typically underutilized.
LTXHWM and LTXEHWM
LTXHWM is the percentage of logical log space a transaction can span before it is declared to be a long transaction and is rolled back by the engine.
John points out that this rollback only affects the session being rolled back (well, excluding any extra strain on the system rolling back a long transaction creates), nothing else is blocked.
LTXEHWM is the percentage of logica…