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Messen
Contributor III
Contributor III

RAM usage increases when making selection

Hi
I have a fairly large QlikView app. Around 85 mill. lines in Facttable. Uses about 15 GB of RAM when opened.

My Straight table has no calculated dimension and 1 expression = '1'  for showing the lines.

So no calculations at all. Just showing lines. Very simple.

When making a selection in one field it takes about a minut for showing the data. The RAM usage of the app increases to more than double up - 35 GB. When data showes up in the table - RAM decreases again to 15 GB.

It doesn't matter whether my selection returns 1 or e.g. 50 lines in the table and doesn't matter whether I'm using Desktop or QlikView Server. Version are 12.10. (I know it is outdated....;-)

Tried different Datamodels : Star with 3 dimensions and all in one Fact table. Which surprisingly enough is faster than the model with 3 dimensions.

I have 25 fields. One field is a text field with average lenght of 100 and max lenght of 1000.

Anyone with suggestions why QlikView has to "unpack" so much data in the RAM for making a simpel selection and best of all - Suggestions for speeding up the time for the app.
 

Thank you in advance for every input 🙂

Regards

Sune

1 Solution

Accepted Solutions
Messen
Contributor III
Contributor III
Author

Dear All

I’m aware of the caching that makes Qlik a unique product. But the behaviour that I experienced is/was not normal compared to my experience with Qlik.

I found a solution. Not WHY the problem was there.

It was my Straight Table which was ‘fuc…’ 😉

Made a new table with same dimensions and the very simple expression. Deleted old one and speed is now what I expect from Qlik. So - something behind the scenes had gone wrong with the old straight table.

 

Thank you all for your contribution ! I’m now a lot better informed about the Qlik cache and Qix engine after reading all the articles 😉

 

Regards

Sune

View solution in original post

4 Replies
marcus_sommer

The behaviour you noticed is called caching and is one of the main-features of Qlik - means most of calculation-results from selections are kept within the RAM and if this selection comes again it won't be new calculated else the cached results will be used. In many scenarios it's a real benefit - but it depends on the underlying data and the kind of analysis.

In your case Qlik tries to cache but discard it immediately because it hits any restriction which I don't know in detail. More background could you find here: The QlikView Cache - Qlik Community - 1468270

Beside this it's useful to limit the rows of large tables with a visibility-condition like:

count(distinct Dim1&Dim2&Dim3) < 10000

Also helpful should be to switch from the straight-table to a table-box which is AFAIK significantly faster as the table-charts.

Further I suggest to look on the cardinality of your fields especially for your mentioned text-field. The RAM consumption is directly related to the max. number of distinct field-values and you may be able to split the field and/or remove not really important information. The logic behind it is here very well explained:

The Importance Of Being Distinct - Qlik Community - 1466796

- Marcus

 

Chip_Matejowsky
Support
Support

Hi @Messen,

In addition to Marcus's excellent suggestions, have a look at article QIX Engine Memory Management and CPU Utilization.  It does a great job in detailing how QlikView utilizes RAM.

 

Best Regards

Principal Technical Support Engineer with Qlik Support
Help users find answers! Don't forget to mark a solution that worked for you!
Brown3391
Contributor
Contributor


@Messen wrote:

Hi
I have a fairly large QlikView app. Around 85 mill. lines in Facttable. Uses about 15 GB of RAM when opened.

My Straight table has no calculated dimension and 1 expression = '1'  for showing the lines.

So no calculations at all. Just showing lines. Very simple.

When making a selection in one field it takes about a minut for showing the data. The RAM usage of the app increases to more than double up - 35 GB. When data showes up in the table - RAM decreases again to 15 GB.

It doesn't matter whether my selection returns 1 or e.g. 50 lines in the table and doesn't matter whether I'm using Desktop or QlikView Server. Version are 12.10. (I know it is outdated....;-)

Tried different Datamodels : Star with 3 dimensions and all in one Fact table. Which surprisingly enough is faster than the model with 3 dimensions.

I have 25 fields. One field is a text field with average lenght of 100 and max lenght of 1000.

Anyone with suggestions why QlikView has to "unpack" so much data in the RAM for making a simpel selection and best of all - Suggestions for speeding up the time for the app.
 

Thank you in advance for every input 🙂

Regards

Sune


Follow this steps it might help you

  1. Restart Your Computer. The first thing you can try to free up RAM is restarting your computer.
  2. Update Your Software.
  3. Try a Different Myloweslife Browser.
  4. Clear Your Cache.
  5. Remove Browser Extensions.
  6. Track Memory and Clean Up Processes.
  7. Disable Startup Programs You Don't Need.
  8. Stop Running Background Apps.
Messen
Contributor III
Contributor III
Author

Dear All

I’m aware of the caching that makes Qlik a unique product. But the behaviour that I experienced is/was not normal compared to my experience with Qlik.

I found a solution. Not WHY the problem was there.

It was my Straight Table which was ‘fuc…’ 😉

Made a new table with same dimensions and the very simple expression. Deleted old one and speed is now what I expect from Qlik. So - something behind the scenes had gone wrong with the old straight table.

 

Thank you all for your contribution ! I’m now a lot better informed about the Qlik cache and Qix engine after reading all the articles 😉

 

Regards

Sune