QlikView Data (QVD) file is a optimized file format for storing QlikView data tables. The file has a binary data format that can be loaded directly to computer memory without any processing required, which makes it the fastest way to load data into a QlikView application. This way of directly loading data into memory is referred to as an optimized load.
In QlikView desktop client this optimized load is indicated by the "Script Execution Progress" dialog showing "qvd optimized" when the QVD file is loaded into memory.
If changes are made to the data or table structure during reload the load will no longer be optimized. In this scenario there is no longer a reference to "qvd optimized" in the
The recommended approach for loading QVD file is to always ensure they are loaded as optimized. If changes are required in the loaded data, then this should be applied through the resident load. This could be done by the principle below, where an optimized load is done to a temporary table which is later dropped.
FROM MyDatya.qvd (QVD);
*, Today() AS TodaysDate
DROP Table TmpTable;