In this post, I've been talking about scalar user-defined functions that are hidden in Actual Execution Plan. There also some queries
that do not appear in Estimated Execution Plans.
Triggers, unlike scalar user defined functions, are totally invisible in the Estimated Execution Plan.
Imagine you have a Customers table and a CustomersLog table. The Customers table has some triggers to log the changes into the CustomersLog table. Below is the trigger body of the insert operation.
INSERT INTO CustomersLog
'Add' AS [Action] ,
GETDATE () AS [DateTime]
'Some Company Name',
The following is the Estimated Execution Plan of the query above:
However, things are differet in Actual Execution Plan: