"Union Query" or in-flow row Append feature

A module to stack data easily would be great. This could be a union join module with a “Union Query” type feature to append rows of data. I’m currently using 4.1.4 as my workflows arent backward compatible with the latest version. I’ll upgrade later when this project has finished but if Union Join is created can it be used across different versions or will it just be created for the latest version. Not asking for too much :slight_smile:

Hello @NikkiB and welcome to the KNIME forum,

do you know the Concatenate node? As I understand this should do what you are looking for. If not, you may want to post a small example with the inputs and output you want to achieve.

Have a nice day,


Cool, thanks. I think I’ve spotted that module before but it only allows 2 datasets to be stacked. Are there any plans for creating unlimited Union Joins with more than two inputs, maybe up to 20 needed in my experience. gasp

Hi @NikkiB ,

You can add multiple further inputs by clicking the “…” on the node (in classic UI)
or by dragging an additional flows onto that point on the node (modern UI). In this way you may Union more than two input flows.

However I believe this may only be in 4.2 or later.

In 4.1, the node might look like this (no dots):

v4.1 is quite an old version now, and it predates my first use of KNIME. Even though the very latest version (5.x) of KNIME may cause compatibility problems for your flows, are you sure there isn’t a “slightly” newer version available that would work for you?

Is there something in particular that you are aware of that is incompatible?

The archive of “old versions” for download is available here: https://www.knime.com/download-previous-versions

It is also possible to have more than one version of KNIME installed (by using the ZIP installation rather than the “setup” executable), and provided you keep the workspaces separate this could be a way forward so that old flows can run in one version, but you have the up-to-date features available for new work.


Thanks @takbb that’s awesome. I didn’t realise you could tap on the elipses for additional inputs. I just tested it and it works in my old version