Incremental loads is a technique used with QVD files. This technique allows you to extract and store in a QVD file only new or modified records. Your source QVD will contain a replica of your source or sources and each time you execute the script, instead of regenerating the file from scratch, you have the possibility of only loading and storing those records that have been modified or are new.
For small sources, incremental loads might not make sense. However, most of the data nowadays is what we call "big". Loading and storing millions and millions of records on a daily basis is not convenient and it is in these cases where incremental loads play a starring role.
Incremental loads are typically used to perform one of the following operations:
- Append
- Insert
- Insert and update
- Insert, update, and delete
