topic Re: Sum() in the script using only one cpu core in QlikView

Sum() in the script using only one cpu core

Thu, 01 May 2014 16:51:30 GMT

Hi all,

today I noticed some strange behaviour during reload of a document - using sum() with Group By is using only one core (of 16). The script is very simple:

GroupData:
Load
     sum(Amount) as TotalAmount,
     Category
Resident MyTable
Group By
     Category
;

When the reload process reach this part of the script it switch to only one core. For a small amount of data is ok but i have ~400M rows in "MyTable". I'm expecting this script to take more than one core or i'm wrong?

Has anyone have experienced the same behaviour?

Thanks!

Re: Sum() in the script using only one cpu core

hic — Thu, 01 May 2014 18:36:21 GMT

I haven't tested this myself, but I would not be surprised if this is single threaded. The "Group by" operation in the script is not so commonly used, so the demand to optimize it has not been there. ("Group by" is usually made in a SELECT, i.e. it is executed by a multi-threaded database. Or it is performed in a chart in QlikView, which is multi-threaded.)

HIC

Re: Sum() in the script using only one cpu core

Clever_Anjos — Thu, 01 May 2014 21:25:39 GMT

"Group by" into a script is a single core operation. No workarounds, unfortunately

Re: Sum() in the script using only one cpu core

Fri, 02 May 2014 04:20:25 GMT

Thanks for the answers.

Somehow i've been living with the idea that is multi core. Any future plans to make it multi core?

Regards!

Re: Sum() in the script using only one cpu core

warfollowmy_ver — Mon, 06 Feb 2017 02:36:12 GMT

Demand for multi-threading on the group in the script of course is, for example, we are working through the terminal server. It is not clear why not do multithreading in groups in a script. Subscribe to the issue two years ago ... Are there any plans in this regard?

I also as a developer much easier to organize the data store in a format QVD and not build individual "workers" requests to the database because at the moment they are more effective and much faster than qlikview.