You can actually set the target field dynamically using a pipeline parameter, but maybe was hard to find in the documentation.
Here is an example that I think will get you on the right track. In this example, the Group By N snap is used like you mention. I set the value to the pipeline parameter _TABLE, which has the value my-table. To do so, use the syntax $[(<pipe param>)] where <pipe param> is the pipeline parameter you want to use, so in this case $[(_TABLE)]. In the preview data, you can see that all documents were aggregated under the value my-table.
Thank you very much for your response. This is indeed helpful and worked as expected. This should be added to the documentation.
Thanks and regards,
Sri
