topic Re: Qlik Sense Server - Buffer files in App Development

Qlik Sense Server - Buffer files

PeterVF — Wed, 04 Sep 2024 12:24:36 GMT

Hi,

I have a question regarding of Buffer load in QlikSence server.

I use in the script: "Buffer (stale after 365 days)" or only "Buffer".
Buffer qvd files are stored in the directory: C:\ProgramData\Qlik\Sense\Engine\Buffers

But the problem is, when I start another application that also uses buffer, all buffer files are deleted and replaced with new buffer qvd files created from actual application.

Why are the buffer files deleted and there are always only those from the last updated application?

Thank you in advance.

Peter

Re: Qlik Sense Server - Buffer files

samuel898 — Thu, 05 Sep 2024 05:08:37 GMT

@PeterVF wrote:

Hi,

I have a question regarding of Buffer load in QlikSence server.

I use in the script: "Buffer (stale after 365 days)" or only "Buffer".
Buffer qvd files are stored in the directory: C:\ProgramData\Qlik\Sense\Engine\Buffers

But the problem is, when I start another application that also uses buffer, all buffer files are deleted and replaced with new buffer qvd files created from actual application.

Why are the buffer files deleted and there are always only those from the last updated application?

Thank you in advance.

Peter

Hi Peter,

The issue you’re experiencing with buffer files in Qlik Sense is likely due to how the buffer mechanism works. Here are some key points to consider:

Buffer File Naming:
The buffer QVD files are named based on a hash of the entire LOAD or SELECT statement and other discriminating information. This means that any change in the script, even a minor one, will result in a new buffer file being created.
Buffer File Deletion:
Buffer files are automatically deleted when they are no longer referenced anywhere throughout a complete script execution in the app that created them. This can happen if the script changes or if a different application runs and creates new buffer files.
Script Consistency:
Ensure that the LOAD or SELECT statements in your scripts are consistent across different applications. Any variation can cause the buffer files to be considered different and lead to the deletion of the previous buffer files.
Variables and Dynamic Statements:
If your scripts use variables or dynamic statements, this can also affect the hash and result in new buffer files being created. Try to minimize changes in the script or use consistent variable values to avoid this issue.
To mitigate this, you might consider:

Keeping your LOAD or SELECT statements as consistent as possible across different applications.
Avoiding dynamic changes in the script that could alter the hash of the statements.

Hope this will help you.
Best regards,
samuel898

Re: Qlik Sense Server - Buffer files

PeterVF — Thu, 05 Sep 2024 07:57:42 GMT

Hi Samuel,

thank you for the explanation and advice on using Buffer Load. I was aware of everything you wrote, and even if I follow it, it doesn't work. I have a feeling that Buffer Load can only be used in one application in QlikSence, but it is not written anywhere in the manual and I did not read about it anywhere.

I recommend everyone who is interested in this topic to do a simple test, where only a simple script will be used in two applications:

QlikSence application 1:

Table1:
Buffer (stale after 365 days)
Load * Inline [
Column11, Column12
1, 2
3, 4
];

Table2:
Buffer (stale after 365 days)
Load * Inline [
Column21, Column22
1, 2
3, 4
];

Exit Script;

QlikSence application2:

Table3:
Buffer (stale after 365 days)
Load * Inline [
Column31, Column32
1, 2
3, 4
];

Exit Script;

After run Load data in the first application, 2 qvd Buffer Files are created, after run Reloading the tables are loaded from these qvd files, which is correct. But after starting the second application, a new buffer qvd file is created and those buffer files from the first application are deleted. I don't understand that logic, Buffer load is useless in QlikSence.

In the past, I used QlikView and buffer files keep there, despite the fact that I used them in several applications.

Or is it related to some setting in QlikSence where it is necessary to set the buffer files to be kept until the application is deleted etc.? But I didn't find such a setting...

Please, can someone help me with this, does anyone have similar experiences?

Peter

Re: Qlik Sense Server - Buffer files

PeterVF — Wed, 11 Sep 2024 07:08:32 GMT

I still haven't received a solution to my problem.

Please, can someone at least confirm that Buffer Load is working for him in QlikSence and what version is he using? Thank you.