All (data) sources used in a report are listed in the "Report" tab. The default source is indicated with a little red star.
Is there a way to change the default data source within the reporting tool or is this just possible by editing the XML?

Yes, it is possible.

Instead of going to the Report Tab, go to any Page under 'Pages'. On the left, you will see the same 'data source' which is actually the package. Right click on it and you will see an option to replace the package. If your package is using DQM then you will also see a + icon to add another package to the report.

Hi cognostechie,
Thanks for the reply.

I'm not sure wether your post answers my question.
I have the situation where I already have more than one data source (e.g. different data modules) in the report. Say data source 1 is the default at the moment and data source 2 is not. How do I switch these two. If I use the option "replace the package" I would probably get errors in the queries, don't I?

Or maybe I don't comprehend you correctly?

I find the term data source confusing.  The term "data source" has a specific meaning in Cognos Analytics.  A data source is created in Cognos Administration on the Configuration | Data Source Connections page.  I don't think that's what you are asking about.

A report can use a data module or a package as a source.  A data source is how a package accesses data.  A data module uses a data server, package, dataset, or uploaded file as sources.

I could assume you are in Reporting looking at the Sources tab in Insertable Objects.  But I don't remember ever seeing a red star next to a package or data module.  I'm also not familiar with a package being the default package.  However, I have not had success using multiple packages in a report.  If I need multiple data subjects in a report, I include them in a data module, then use the data module for the report.

Please be specific and use correct vocabulary.

Quote from: dougp on 08 Oct 2024 06:03:30 PMBut I don't remember ever seeing a red star next to a package or data module. 

He is not talking about the screen which shows Insertable Objects but the screen you get when you click on Report and then again Report.

Quote from: dougp on 08 Oct 2024 06:03:30 PMHowever, I have not had success using multiple packages in a report. 

It is only possible when the package you use uses DQM. You will get a '+' icon on the top right side of the package to add another DQM package. 

I must have overlooked it, I'm sorry for the confusion:

There is (!) an option to set a package (data module) as default. Simply right click on the "not yet default" package and select "set default package". It is quite useful, e.g. when you create a new query: it does select the default package as the "source package" for that query. By that you can avoid the hustle of always having to change the "data source" of the query.

Quote from: dougp on 08 Oct 2024 06:03:30 PMI find the term data source confusing.  The term "data source" has a specific meaning in Cognos Analytics.  A data source is created in Cognos Administration on the Configuration | Data Source Connections page.  I don't think that's what you are asking about.
[...]
Please be specific and use correct vocabulary.

In the query tab in reporting, the entry in the properties pane where you select your default package is actually labeled "data source". So I guess the term is not exlusively reserved for the artefacts in Cognos Administration > Data Source Connections.
And how am I to address both "old" packages and "new" data modules with one term? To me these are data sources of the specific report. Or is there another common term for them?

Quote from: cognostechie on 08 Oct 2024 08:12:08 PMIt is only possible when the package you use uses DQM. You will get a '+' icon on the top right side of the package to add another DQM package. 

I am aware.  It has just never worked well for me.  And it's not much more work to create a data module to combine the packages.

Quote from: MrKlar on 09 Oct 2024 06:23:46 AMIn the query tab in reporting, the entry in the properties pane where you select your default package is actually labeled "data source".

I have never even noticed that property because there are other ways to manage that.

Delightful.  There are multiple definitions for the same term in a single ecosystem.  Well, as long as we keep the users confused, we'll always be employable.

Quote from: dougp on 09 Oct 2024 01:14:33 PMI am aware.  It has just never worked well for me.  And it's not much more work to create a data module to combine the packages.

Your choice but I have never experienced any trouble with it. Creating a Data Module is an extra maintenance when the packages are already there.