As QlikView is IN_MEMORY tool we need to load all data to analyse but consider that your company has very vast database (say in billions) and it is not viable (sometimes) to load all data… here comes Direct Discovery.
Direct Query allows QlikView to connect to data source without loading all data in to memory. To do this we have to load only Dimensions. QlikView generates query to retrieve required data from the database.
But of course this is having disadvantages also. Your response time is now dependent on how fast your data connection is. Below points need to be consider
1) Only one Direct Query Table per application is supported
2) Set Analysis, Complex Calculations not supported (only sum, count, min, max, avg supported)
3) You can’t search direct field in normal search
4) Section access will not necessarily work against Direct table
5) Loop and Reduce in publisher will also not work for Direct Table
