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Not applicable

optimize and non-optimze load in qvd

Hello can any one help me to under stand the difference b/w

optimize and non-optimze load in qvd .

1:-which one is better and why ?

2:- one one scnerio for each .

Thanks .

1 Solution

Accepted Solutions
MVP & Luminary
MVP & Luminary

optimize and non-optimze load in qvd

Optimized load is much faster and therefore preferable, especially for larger data sets.

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.

cheers,

Oleg

14 Replies
MVP & Luminary
MVP & Luminary

optimize and non-optimze load in qvd

Optimized load is much faster and therefore preferable, especially for larger data sets.

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.

cheers,

Oleg

aboumejjane
Contributor

optimize and non-optimze load in qvd

Hi There,

For more info regarding optimized and unoptimized qvds, please read the artical of Rob Wunderlich:

http://qlikviewnotes.blogspot.com/2008/05/when-less-data-means-more-ram.html

Cheers,

iSam

MVP
MVP

optimize and non-optimze load in qvd

Hi

I believe that it is no longer necessary to make mapping table loads not optimised (v11 and on).

Regards

Jonathan

Logic will get you from a to b. Imagination will take you everywhere. - A Einstein
Not applicable

optimize and non-optimze load in qvd

Hello,

On one hand we say that we should have try and have all the calculations in the script itself rather than putting them in the Dashboard & on the the other hand if we do that the load would no longer be Optimized. What to do then, how to have the expressions in the script itself and still make the load Optimized

Regards

Not applicable

Re: optimize and non-optimze load in qvd

I just found that when doing a

Load * From ...

the load will not be optimized. Only when I do a load with all fieldnames listed an optimized load is performed:

Load Field1, Field2, Field3 From ....

QV 11, I don't know if this behaviour is new in this release

Not applicable

Re: optimize and non-optimze load in qvd

hi,

The article by Rob states like this.

"Consider a QVD file with one million rows. The QVD was loaded from a database and contains two fields:

aNum – unique integers, 1M unique values.
aDate – dates distributed equally throughout 2000-2003, 1,460 unique values.


QV stores each of these values as integers, occupying 4 bytes of RAM each. Nice and compact."

Does this mean that the values in a QVD are stored as integers? Can anyone explain how the data is stored internally in a QVD?

Thanks,

Maria

Not applicable

Re: optimize and non-optimze load in qvd

hi,

Can anyone please confirm this point? Is it necessary to make mapping table loads not optimised from version 11?

Thanks,

Maria

Not applicable

Re: optimize and non-optimze load in qvd

No, it is not necessary to have unopt. load for mapping Loads..for sure

jt0803aa
New Contributor III

Re: optimize and non-optimze load in qvd

Hi Maria

i was also wondering how data is stored on the QVD did you get any answer?

thanks a lot