In a QVD which is created by QVW ..what is the com... - Qlik Community

deepali_more · ‎2016-03-03

In a QVD which is created by QVW ..what is the compression ratio ?

Message was edited by: deepa more

alexdataiq · ‎2016-03-03

AFAIK QVD's aren't compressed. They use a clever way of storing (using symbols/data tables and bit-stuffed pointers) to optimize the loading speed of the data (10-100x faster).

deepali_more · ‎2016-03-09

If QVDs are using symbols for the fast retrieval that means it is compressing the data to store it in clever way..Right?

I wanted to know what ratio to its original data this rate is..

One of the interviewer asked me this question.

vikasmahajan · ‎2016-03-15

Hi,

When you extract any data source file it stores as qvd. The qlikview stores data In QVD In encrypted form. So data are compressed In QVD. If a data source file is of 10 MB size. When its convert into QVD then size reduces up to 90%. So in QVD size of data is near about 1 MB.

http://www.adivaconsulting.com/qlik-view-business-intelligence/item/113-data-compression-in-qlikview...

http://www.quickintelligence.co.uk/qlikview-qvd-files/

http://community.qlik.com/message/476739#476739

HTH

Vikas

Hope this resolve your issue.
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swuehl · ‎2016-03-15

I believe there is no the one and only compression ratio (or file size of QVD compared to source size, if you prefer), it will greatly depend on your data.

If you've got only unique numbers, you probably won't see any reduction in size, and maybe even a larger QVD.

So I guess the answer to the interview question is 'it depends on...'.

alexdataiq · ‎2016-03-15

Just to clarify. QVD files aren´t encrypted. QlikView has no built-in functionality for that, but maybe you could define a encryption/decryption function in a macro and use it in the load script.

Regards.