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debayanroy
Contributor
Contributor

Memory Management in Qlikview

Hi All,

Can anyone explain what will happen if I have a data model whose qvw file is of 50GB and ram on the server is 50GB And the user tries to open another document parallely ? Since Qlikview is an in-memory tool, there will be memory blockage on the ram. How to solve this problem.

3 Replies
oknotsen
Master III
Master III

If you have a data model that is 50gb and the ram on the server is 50gb, you made some serious mistakes when making the hardware estimates or have not been paying attention to your server the last few months / years .

A model that takes up 50gb will never work on a 50gb ram server to begin with, as it leave no room for your OS and user sessions.

Both QlikView and Qlik Sense are "in memory" tools. Without memory, they simply wont work. Swapping simply is not an option.

Luckily for you, Qlik uses a lot less bytes as that same data takes in its source system.

May you live in interesting times!
debayanroy
Contributor
Contributor

No, the above is an hypothetical scenario. I really want to know what will happen if such kind of circumstances persist. Is there any alternative or round-robin mechanism to swap apps to user. Anything on server level will do.

The server on which I work has 512GB RAM and my app is <=5GB. So luckily for me no issues.

oknotsen
Master III
Master III

512gb is a decent size server sir.

That means that the person who installed your server will hopefully have adjusted the default values for "Working Set Low" and "Working Set High" (not sure if those are the current names; might have changed) to higher numbers.

On a standard server these values would be 70% for low and 90% for high. For 512gb these have probably been changed to 90% and 95% (depending on your specific situation).

Up to "low", the server will eat up the memory for caching to speed up the app for future people asking for the same selection. However, you open more apps and more sessions and those also eat memory. That means it will remove cached stuff (and long inactive sessions) to stay up or below 70%.

When above that, your are slowly running into trouble. But of course you are keeping track of your resource logs. When your server is above "low" on a constant basis, it is time to jump in your car and get more memory.

When it reaches "high", it is time to say farewell to your server as it will no longer function. The moment Qlik needs to start swapping your server will either crash or your app will work at 1/1000 of the normal speed so your user will be complaining.

It is your talk (or.. well.. who ever manages the server) to keep track of memory usage to avoid running into this situation.

May you live in interesting times!