Concatenate tables error handling

I’m new to error handling in Knime and find it quite confusing. If I try to concatenate 2 tables but sometimes the 2nd table is missing data the concatenate node fails and data won’t pass through it. Is there a way to force the data to pass through if a table is missing data?


In case of missing values ("?") there shouldn’t be any problem but if you have missing columns, you can select the “Use union of columns” option in the configuration window of the “Concatenate” node.


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Hi armingrudd,

What I am experiencing is that when one of the inputs is an empty table the concatenate node will not allow data to pass through. I tried the concatenate (optional in) node but that also did not seem to work.



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Hi there!

I couldn’t get error when one table is empty and I preform concatenation with Concatenate node. What is the error you are getting? Can you share a workflow maybe?