Joiner / Vlook-up in KNIME question


I am quite new to KNIME and for the last hours I’ve been going crazy.
I have two tables:

Table A

Table B
Table B

I want to join these 2 tables based on the country. In Excel I would VLookup the other columns based on the Country column. In KNIME, I’ve tried using Joiner but I am getting almost 800.000 rows when in reality it should be the same number of rows as in Table A.

Any idea what I am doing wrong?

Thank you!

Your table B may have duplicates by Country, say with different zones or region, so on.
Also take in account that Vlookup most likely corresponds to Left Outer Join of table A with table B.

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Hi @CK24_SH

In a Joiner you most likely want to choose a column (or columns) which make a row unique in a table. If you join on non-unique columns you get an exponentially growing result-table.
If a value of Country appears 10x in table A and 40x in table B this will give you 400 rows in the result.

If possible you can use a GroupBy node to make a table with unique rows for a Country, before the join is made.


If you want to deal with duplicates this article might be for you


Thank you, this worked.

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Thank you very much :slight_smile:

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