Yes it is an event calling procedure.
Generally I think there is some problems with events in PXC 5.7. For example in my situation (3-node cluster). The Events are only enabled in 1st node by default. If 1-st node is crash then the events are not enabled in one of the other 2 nodes automatically. Even if I forced to enable in one of other 2 nodes after crash, although status of events show enabled, actually doesn’t work.
Means that events are only works in 1-st node - originated node.
Is it really work principle of events in PXC 5.7? If yes then it is the problem for cluster and hope to be solved in following releases or can be solved with patch or bug fixes.
If there is any documentation or blog which explain events detailed, please inform me.
Thanks.