topic Re: How qlikview stores data internally when qvd's are not there? in QlikView

How qlikview stores data internally when qvd's are not there?

Anonymous — Wed, 25 Nov 2020 16:16:04 GMT

Hi everyone,

Iam very new to Qlik .Iam really very confuse about this. Qlikview stores data in qvd's .As of i know , qvd saves data in binary format(bit's and pointers ,de-duplicated values) by using this retrieving data from qvd's is faster.My doubt is if i load data from any source without creating qvd's ,directly into script in this case also data stores in binary format if not how data stores if qvd's are not there?. i understood the concept of symbol, tables and bit stuffed pointers and my doubt is symbol, tables and bit stuffed pointers are created only in qvd's or for evry data load into qlikview?

Thanks and Regards

Seenu.

Re: How qlikview stores data internally when qvd's are not there?

rubenmarin — Mon, 04 Jun 2018 18:05:46 GMT

Hi Seenu, the qvw stores all data and design and pointer and bit stuffed pointer, qvds are used to reload data faster it's just another source of data, but this is the fastest way to load data in QlikView.

I'm not sure if qvds stores the symbol tables, but think that 2 different qvds can add data to the same field while reloading, so the pointer table needs to be created in the qvw.

Edit: based on documentation symbol tables are included in qvds:

https://help.qlik.com/en-US/sense/April2018/Subsystems/Hub/Content/Scripting/work-with-QVD-files.htm#anchor-4

Re: How qlikview stores data internally when qvd's are not there?

Gysbert_Wassenaar — Mon, 04 Jun 2018 18:05:48 GMT

Qvd files are basically memory dumps of individual tables of a qlikview document. So all the data is in the qlikview document and can be stored to disk in qvd files.

Re: How qlikview stores data internally when qvd's are not there?

Anonymous — Tue, 05 Jun 2018 04:52:52 GMT

Hi,

Thanks for your responses Ruben and Gysbert.I understood that storing data in pointers is not specific to qvd's.But why qlikview retrieves data very fast from qvd's.

Thanks and Regards

Seenu.

Re: How qlikview stores data internally when qvd's are not there?

marcus_sommer — Tue, 05 Jun 2018 06:38:33 GMT

An optimized qvd-load and also opening a qvw or loading binary from a qvw means that nearly no processing of the data is necessary (only a few meta-data needs to be handled which is almost always negligible) because the data are already within the format how they needs to be in RAM and it's just a transferrering from the storage into the RAM.

- Marcus

Re: How qlikview stores data internally when qvd's are not there?

anandsai4u — Tue, 05 Jun 2018 07:42:33 GMT

Hi Seenu,

QVD's will store the data with 1-10 times of compression of original qvw data.

A QVD file is a native QlikView file format optimized and compacted for speed when reading data from within a QlikView load script. Reading data from a QVD file can be 10-100 times faster than reading records directly from other data sources. A QVD file contains a single table of data from a QlikView application.

Regards

Anand Sai

Re: How qlikview stores data internally when qvd's are not there?

rubenmarin — Wed, 06 Jun 2018 07:46:15 GMT

Hi Anand, just to advise that sometimes qvd are bigger than the qvw, it's easier to see with big qvds.

Qvds are used to reload faster, reduce number of access to databases, organize data.... but I wouldn't say that saving space is one of the advantages.

Regards.