performance

[#1]

Hi,

  I have few queries related to performance reducing the online calculation time.

      1. Is there any way to identify the calculation time of the individual expression. Suppose i have a pivot table and it has 20 expressions and i want to know the calculation time of each individual expression. I want this to identfiy to reduce the online calculation time.

      2. As a part of the reusablility we have stored the expression in the spreadsheet and using the expression for the muliple charts and pivot tables. Will variables cause the performance impact in the online calculation. Which one has the better performance using variables or the actual columns in the expressions.

[IAMDV]

Hi Mate,

Barry had written a detail post on what you are looking for... here is the link.

He demostrated the performance benefits on re-using the expressions and labels. You can also see on how to test the calculation time of expressions.

I hope this helps!

Cheers - DV

[#3]

Thanks for your response.

I am storing the variable in the excel and reusing it .It almost takes 2 min in online to calculate. It is huge impact interms of performance.

I would like to know if tables A (Huge data with some duplicate values) & B (Very less data) are assoicated and if i write a expression with a column from A and coumn from B using the variables. Will it be there any performance reduction comparing to expression from a single table.

[IAMDV]

Hi Again - I am not sure why you are storing the variables in Excel. It is good practice to join the tables wherever possible. If you have too many distinct values then QV takes more time compared to non-distinct values. How big is your data set?

I am giving you detailed summary on how things work internally when you load the data in QlikView... here you go.

The data records are read into the memory, so that all the processing of data may be done through memory. I am sure you know this bit. QlikView treats all the data as Data Element Type (Columns / Fields) and Data Element Values (Values / Records). So each different data element value of each data element type is assigned a binary code and the data records are stored in binary-coded form and they are also sorted. By using the binary coding, very quick searches can be done on the tables. Also, QlikView removes the redundant information information and reduces the amount of data. However, the redundant information in stored as seperately with the frequencies for each unique data element value and across each data element type. When user makes a selection on data element values then the implied selection (possible values) are kept track seperately to present them to the user. By this process QlikView can perform rapid linear searches.

Cheers - DV

[#5]

Thanks DV,

Considering the number of expressions and the amount of data it is going to grow , rather using expression i would go with the pre aggregated data to reduce the online calculation time and improve the performance.