The default behavior of Query operations is to apply special rules:

Use the ordinary behavior of Missing:

Statistics functions on list of objects ignore Missing objects by default in Query operations:

They act in the same way on Dataset operations:

Using MissingBehaviorNone makes Missing objects be preserved:

This would be equivalent to direct action of Mean on the list or Dataset object:

Statistics functions on lists of insufficient length return Missing["Indeterminate"]:

Some operations with variable number of arguments ignore Missing objects by default in Query:

They act in the same way on Dataset operations:

Using MissingBehaviorNone makes Missing objects be preserved:

Other operations return Missing["Indeterminate"] by default:

Using MissingBehaviorNone makes Missing objects be preserved:

Structural and extraction operations in Query always preserve Missing objects:

The value of the MissingBehavior option does not affect the result:

Dataset[…][f] is equivalent to Query[f][Dataset[…]] and uses default settings for MissingBehavior:

Use Query[f,options][Dataset[…]] to pass options to the Query operation:

Mathematical Query operations can return Missing["Indeterminate"] by default in invalid cases:

Specify MissingBehaviorNone to change to Failure results: