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mwallman
Creator III
Creator III

Qlik Performance: What does it mean when someone says "Single Threaded" operations and Multi-Thread?

Hi all,

In Qlik what does it mean when someone refers to single threaded and multi-threaded operations?

What are some examples of each?

Which one is recommended for good performance? And which one is to be avoided?

1 Reply
ramchalla
Creator
Creator

@mwallman  if i have to say in simple terms, when data is getting processed,  based on the operation that you have specified, data will be split in multiple data sets and each data set will be taken care by single thread and sometime data will get processed by only single thread where the split will not happen.

Multithreading:

if you use Sum(Sales) as an expression on any data set, data will be split into multiple sub data sets and each sub data set will be taken care by each thread. For example, if you have 500 MB data and you want to aggregate the Sales amount, first this data will be divided into some blocks, assume 5 blocks. Sum(Sales) will be executed for each block by using one thread and the final results for each block will get added and we will have the final result. we call this a multithreaded operation where multiple threads process sub sets of data and the execution will be faster as it is a parallel processing. There will be no search operation performed.

Single Thread:

if it is single threaded operations, processing will be done on entire data sets and only one thread will work on it.

for example, if you use count(distinct Employees) as an operation, Data will not get split into multiple blocks. Search will be performed on entire dataset to find the unique values. So this operation will be slower.

please refer the below links to understand the best practices.

 

https://help.qlik.com/en-US/sense/September2020/Subsystems/Hub/Content/Sense_Hub/Apps/app-performanc... 

https://help.qlik.com/en-US/qlikview/April2020/Subsystems/Client/Content/QV_QlikView/application-per...