Lineage of Applications which Generate QVDs

[Kerbecs]

Hello. I apologize if my question is too simple but I am quite new to Qlik. I have been exploring Qlik APIs specifically the Engine API. The Engine Explorer is able to generate lineage for stream apps or client facing apps. However I can't find a way to generate lineage for apps which are making the QVDs. Is there any way to achieve this? I would like to get the data source details of the QVDs

[rwunderlich]

The Apps that generate the QVDs will also provide lineage information from the Engine GetLineage method. One of the challenges here is that Lineage information is not present if the table is dropped in the scrip, which is common in QVD generator apps. e.g.

Tab1:
SQL Select * From ...;
Store Tab1 into ....;
Drop Table Tab1;  // No lineage data for Tab1

-Rob

[Kerbecs]

I see. The problem I am facing is that reporting apps are showing up in the Engine Explorer but Apps which generate the QVDs are not there. Basically the output Applications are being displayed as options but not the intermediary apps which feed the output apps.

So if it the flow is like Data Source -> QVD App -> Report App then in the Explorer I can only see the Report Apps and that the data is stemming from the QVD but cant see the Data Source.

[rwunderlich]

Could that just be a permission issue? Do you see the QVD generator apps in the hub? Is this Cloud or on-prem?

-Rob

[Kerbecs]

I can't see the QVD generator apps in hub but I can see them on QMC. I can see only the streams and report apps on hub. This is on-prem I believe. Is this a permissions issue then? Once again apologies if my questions and replies seem quite simple and vague. Just a whole lot to take in for a beginner. 

[Kerbecs]

Nevermind I got the extract app to show up in Engine Explorer but like you said as tables are being dropped, Lineage isn't being generated. Anyway to resolve that?

[rwunderlich · Accepted solution]

There is a clever hack you can use to keep the lineage data from being dropped.

A DROP TABLE statement will remove <LineageInfo>  if there are no prior
<LineageInfo> elements in the stack.

In practical terms this means if you load a table at the top of your script that doesn't get dropped, you won't lose any lineage data from dropping subsequent tables. Put this at the top of every script:

LineageDummy:
Load 'dummy' AutoGenerate 0;

-Rob
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