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fmazzarelli
Contributor III

Extension .qvd

Immagine.pngI'm looking at the examples included in the program and use of files known .qvd . What you are or how you carry ?

1 Solution

Accepted Solutions
awhitfield
Esteemed Contributor

Re: Extension .qvd

Hi Fabio,

this is from the Qlikview Reference Manual:

QVD Files

A QVD (QlikView Data) file is a file containing a table of data exported from QlikView. QVD is a native

QlikView format and can only be written to and read by QlikView. The file format is optimized for speed

when reading data from a QlikView script but it is still very compact. Reading data from a QVD file is typically

10-100 times faster than reading from other data sources.

QVD files can be read in two modes: standard (fast) and optimized (faster). The selected mode is determined

automatically by the QlikView script engine. Optimized mode can be utilized only when all loaded fields

are read without any transformations (formulas acting upon the fields), though the renaming of fields is

allowed. A WHERE clause causing QlikView to unpack the records will also disable the optimized load.

A QVD file holds exactly one data table and consists of three parts:

1. A well formed XML header (in UTF-8 char set) describing the fields in the table, the layout of

the subsequent information and some other meta-data.

2. Symbol tables in a byte stuffed format.

3. Actual table data in a bit-stuffed format.

28.1 Purpose of QVD Files

QVD files can be used for many purposes. At least four major uses can be easily identified. More than one

may apply in any given situation:

Increasing Load Speed

By buffering non-changing or slowly changing blocks of input data in QVD files, script execution becomes

considerably faster for large data sets.

Decreasing Load on Database Servers

The amount of data fetched from external data sources can also be greatly reduced. This reduces work load

on external databases and network traffic. Furthermore, when several QlikView scripts share the same data it

is only necessary to load it once from the source database into a QVD file. The other applications can make

use of the same data via this QVD file.

Consolidating Data from Multiple QlikView Applications

With the Binary (page 225) script statement it is possible to load data from only one single QlikView application

into another one, but with QVD files a QlikView script can combine data from any number of Qlik-

View applications. This opens up possibilities e.g. for applications consolidating similar data from different

business units etc.

Incremental Load

In many common cases the QVD functionality can be used for facilitating incremental load,

 

HTH - Andy

 

1 Reply
awhitfield
Esteemed Contributor

Re: Extension .qvd

Hi Fabio,

this is from the Qlikview Reference Manual:

QVD Files

A QVD (QlikView Data) file is a file containing a table of data exported from QlikView. QVD is a native

QlikView format and can only be written to and read by QlikView. The file format is optimized for speed

when reading data from a QlikView script but it is still very compact. Reading data from a QVD file is typically

10-100 times faster than reading from other data sources.

QVD files can be read in two modes: standard (fast) and optimized (faster). The selected mode is determined

automatically by the QlikView script engine. Optimized mode can be utilized only when all loaded fields

are read without any transformations (formulas acting upon the fields), though the renaming of fields is

allowed. A WHERE clause causing QlikView to unpack the records will also disable the optimized load.

A QVD file holds exactly one data table and consists of three parts:

1. A well formed XML header (in UTF-8 char set) describing the fields in the table, the layout of

the subsequent information and some other meta-data.

2. Symbol tables in a byte stuffed format.

3. Actual table data in a bit-stuffed format.

28.1 Purpose of QVD Files

QVD files can be used for many purposes. At least four major uses can be easily identified. More than one

may apply in any given situation:

Increasing Load Speed

By buffering non-changing or slowly changing blocks of input data in QVD files, script execution becomes

considerably faster for large data sets.

Decreasing Load on Database Servers

The amount of data fetched from external data sources can also be greatly reduced. This reduces work load

on external databases and network traffic. Furthermore, when several QlikView scripts share the same data it

is only necessary to load it once from the source database into a QVD file. The other applications can make

use of the same data via this QVD file.

Consolidating Data from Multiple QlikView Applications

With the Binary (page 225) script statement it is possible to load data from only one single QlikView application

into another one, but with QVD files a QlikView script can combine data from any number of Qlik-

View applications. This opens up possibilities e.g. for applications consolidating similar data from different

business units etc.

Incremental Load

In many common cases the QVD functionality can be used for facilitating incremental load,

 

HTH - Andy

 

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