QVD s are faster why

[#1]

Hi,

I have the doubt like by using QVDs data is compressed so generally to decompreess it and use as a original source file it should take time right but qvd s are faster and i read the blogs qvd are also not so much decomressed like zip and un zip like real world compression techniques.iam interested to know how these are compressed and faster performance these are giving

give me comments

regards

Mahesh

[Gysbert_Wassenaar · Accepted solution]

Qvd files can be loaded very fast because the data is already in the same format as Qlikviews internal database. It's kinda of like a data dump of part of the in-memory database. Qvd files themselves are not compressed. The compression comes from using bit-stuffed pointers. You've already read the blog post explaining that I think.

[Peter_Cammaert]

QVDs are compressed uring the same technology that QlikTech also uses to compress data in-memory. So if you load a QVD straight into memory (e.g. without a WHERE clause causing forced decompression) almost no operation needs to be performed on the QVD contents.

If you want to know how exactly they do this, there must be some patent application with details somewhere. But don't ask me where it is, I just like the magic in all of this.

Best,

Peter

[#4]

Thank u get satisfied with ur answer

[#5]

Hi,

find copy of attachment...