topic Re: QVD in QlikView

QVD

NavinReddy — Tue, 24 Dec 2013 04:43:23 GMT

Hi All,

Help me some one This Query

How could you say QVD is Optimized ? some one as asked this Question

Thanks in Advance

Niranjan

Re: QVD

Anonymous — Tue, 24 Dec 2013 04:51:03 GMT

When you are loading a qvd with no where condition in it or without using any of the calculation function in the load script ,

then the reload from the specific qvd will be optimized otherwise it will not be optimized.

Optimized load is much much faster than the normal one.

Regards

Nitin

Re: QVD

Siva_Sankar — Tue, 24 Dec 2013 04:51:55 GMT

Optimized loads are possible if no transformations (calculations) are made during the load, and no (almost) filtering is done in a WHERE clause.

The only acceptable filter is using function Exists:

WHERE Exists(Field)

So for example this load can't be optimized.

Load * From ... WHERE Country = 'US

but this load can:

Load * From ... WHERE EXISTS(Country)

================================

On the other hand, the only time you want the load not to be optimized, is if you load a Mapping table from a QVD file. In this case, Optimized load doesn't quite work, so you want to make the load non-optimized deliberately.

Regards,

Siva

Re: QVD

NavinReddy — Tue, 24 Dec 2013 05:05:43 GMT

Hi Guys Thanks for your reply,

But what i am asking is

When i m fetching data from data source it is like 100MB,

when i m storing same data in to QVD format it is like 70MB ,

How it possible,it is optimized or not (one interviewer asked this Question)

Thanks In Advance

Niranjan

Re: QVD

Siva_Sankar — Tue, 24 Dec 2013 05:09:20 GMT

Niru,

When storing the data from the source to the QVD it is compressed and optimized.

But, when you load the QVD like...

Load * from name.qvd... it is optimized.

Load * from name.qvd where x=y(or any condition); it is unoptimized.

Meaning if there is no changes done on the qvd and loading straightly from the QVD It is optimized

Regards.

Siva

Re: QVD

Anonymous — Tue, 24 Dec 2013 05:15:05 GMT

When data is stored in QVD format, by fetching data from data source, its being compressed.

but its not optimized.

QVDs are not optimized while the loads are optimized when there is not calculations done or no where condition is available.

Re: QVD

NavinReddy — Tue, 24 Dec 2013 05:18:23 GMT

Hi Siva,

storing the data from the source to the QVD it is compressed and optimized.

in this point you discussed compressed and optimized ,he is asking this question

he explained some thing like

when you storing data in qvd format it could avoid duplicates with same names,

Can you please explain me more about compressed and optimized.

Thanks & Regards

Niranjan

Re: QVD

Siva_Sankar — Tue, 24 Dec 2013 05:32:18 GMT

Niru,

QVD : Stands for Qlikview Data (One of the optimize layer of data which has been fetched from the database, qvd is a patent technology of qliktech and qlikview applications reads data 100 time faster as compared to any other sources because data get stores in optimized format. Only Qlikvew application can read the data from QVD. Its always better to fetch the data from from database first and then load the data into your application)

Find the below link to know more about QVD.

http://www.learnallbi.com/qvds-in-qlikview/

Regards.

Siva

Re: QVD

Siva_Sankar — Tue, 24 Dec 2013 05:36:33 GMT

Refer the below too.

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

Regards.

Siva

Re: QVD

Tue, 24 Dec 2013 06:25:10 GMT

It Store data in XML format, hence it is compressed

Re: QVD

Tue, 24 Dec 2013 10:54:30 GMT

Hi Niranjan,

When we load data from any source into Qlikview, the data are compressed in a way of array pointer concept.

Ex:- In a table we have 2 fields and 10 rows.

F1	F2
A1	10
B1	20
A2	30
B2	40
A1	50
A2	60
B1	70
A1	80

While loading into Qlikview it consider the above data as given below.

Considering the value A1 once and identifying the occurence of the value in the form of pointer. Physically A1 is appearing once and the count of occurence is 3. By doing this the amount of space is less and hence the data are compressed.

Hope this helps!

Vinoth

Re: QVD

ngulliver — Tue, 24 Dec 2013 11:58:58 GMT

Hi, Niru Niru.

Have a look at this article on Optimisation. It may help you.

http://www.quickintelligence.co.uk/qlikview-optimised-qvd-loads/

Regards,

Neil