{"id":26203,"date":"2018-08-28T03:30:30","date_gmt":"2018-08-28T03:30:30","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=26203"},"modified":"2021-12-07T11:25:08","modified_gmt":"2021-12-07T05:55:08","slug":"qvd-files","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/qvd-files\/","title":{"rendered":"What are QVD Files – Creating QlikView Data Files"},"content":{"rendered":"

In our last session, we talked about QlikView Navigation Pane<\/strong>. Here, we will discuss QVD Files.\u00a0Qlikview Data Files<\/em> are known as QVD files.<\/p>\n

In this QVD Tutorial, we will discuss the modes and role of QlikView Data Files in QlikView Architecture<\/strong>.<\/p>\n

Along with this, we will cover the componenets, advantages and steps to create QVD Files.
\nSuch data files contain tables having data, created in and exported from QlikView. QVD files are exclusive to QlikView and can only read and written in QlikView.<\/p>\n

Let us know more about QVD files through this tutorial.<\/p>\n

What are QVD Files?<\/h3>\n

QVD files are a gift to QlikView as they are significantly faster to load and process. It is claimed that processing these files is 10 to 100 times faster than the usual files.<\/p>\n

These files can store a large amount of data and also has the document format of the main Qlikview file. QVD files are already loaded from the data source and reside in the in-memory which makes data fetching very easy.<\/p>\n

Such files carry compressed data of the main Qlikview document and are always saved along with the main document. One qvd file contains the data of only one Qlikview document and not multiple.<\/p>\n

In order to save a QVD file, you have to type a special command within the script defining a proper path for the file and mentioning the .qvd extension.<\/p>\n

Modes of QlikView Data Files (QVD)<\/h3>\n

There are two modes in which a QVD file can read (fetched or processed to view).<\/p>\n

a. Standard Mode<\/p>\n

b. Optimized Mode<\/p>\n

Which mode is required is decided by the QlikView script engine and it is automatically selected. The basic difference between the two is that in standard mode file is read fast but in optimized mode, a file is read even faster.<\/p>\n

The only condition with the optimized mode is that the file must only read, and no transformation or calculations must do, as any interfering statement would disable the optimized mode. If any transformations are done, then the .qvd file switches to a standard mode.<\/p>\n

Role of QVD Files in QlikView\u2019s Architecture<\/h3>\n

QlikView files hold great importance in the three-tier architecture of QlikView. There are three tiers of the QlikView architecture. To understand it in simpler words, in the first tier<\/em>, data is loaded from the database (source) and then these data files are stored as QlikView data files.<\/p>\n

The QVD files comprise the second layer<\/em> of the QlikView architecture. It acts as the middle layer between the front end<\/em> and the back end<\/em>. In the backend lies the database and at the front end are binary QVW\u00a0files which are used for presenting data to the front-end users.<\/p>\n

The role of QVD files between these two ends is of transition files i.e. data files loaded from a database and are stored in QlikView\u2019s memory as QVD files so that it is easier and faster to fetch data from memory than having to connect every time to the database.<\/p>\n

These QVD files are again transformed into QVW files which are ready for display and presentation for analytical purposes. This makes the third tier.<\/p>\n

\"Role<\/a>

Role of QVD Files in QlikView\u2019s Architecture<\/p><\/div>\n

Components of QVD File<\/h3>\n

Any QVD file is comprised of three main components,<\/p>\n