The previous approach was simplistic and could result in inefficient queries
in certain edge cases, notably causing MongoDB to not utilize existing indexes
when querying by last inform timestamps given upper and lower bounds. The new
implementation leverages our existing expression minimizer code and can
therefore generate more efficient queries or at least queries that can take
advantage of existing indexes.
This also modifies the behavior of AND/OR operators to strictly return
true/false/null whereas previously they could return the value of the
first truthy/false operand. The purpose of this change is to maintain
expression equivalency before and after minimization.
Zaid Humaimidi
Shweelan Samson