Optimized QVD in Qlikview

while creating QVD file when you press reload in Edit script window you can observe there it display the file optimized (when you done fetching all the data)



The Qlikview create and compress and store the data into QVD. An optimized load the data is sent directly from disk to memory directly in the same compressed format.
and the QVD loads with a WHERE (EXISTS)

Some examples of things that will cause a non-optimised load are:
- Adding new fields to the table
– Deriving new values from a field in the QVD
– Retrieving a field twice
– Most WHERE conditions
– Joining to an existing in memory table
– Loading data into a mapping table
In contrast the things you are allowed to do are:
- Rename fields
– Omit fields
– Do a simple one field WHERE EXISTS on a field returned in the record set