Monitoring Apply Lag on Logical Standby
I've got a logical standby DB being monitored by EM12c. and its all working fine. When the apply starts to lag then I get warnings when it goes over thresholds which is perfect.
However last night we had a problem in that the apply processes stopped on the logical standby - this means that the apply lag and apply finish time values both return NULL values (the graphs in EM have gaps in them).
Obviously this is a bad thing as the DB falls rapidly out of sync... but EM12c doesn't report an issue because the value isn't greater than zero.
1