Difference between Peek() and Previous() function

[Andreas_Giesbrecht]

The two functions Peek() and Previous() are similar, but still fundamentally different. Previous() operates on the input to the Load statement, whereas Peek() operates on the output of the Load statement.

This means that it makes a big difference for Peek() if a field is included in the Load statement or not. But it doesn't affect Previous() at all.

Further, the two functions behave very differently if you combine them with a where clause: Previous() will look into the previous input record, whether this record has been accepted or not by the where clause. But Peek() will look into the last accepted record - the last record that passed the criterion of the where clause, which may be 5, 10 or 100 records back.

See more on Peek() vs Previous() – When to Use Each

Environment:

Qlik Sense Enterprise on Windows 
QlikView 
Qlik Cloud 
Qlik Sense Business