There are known limitations with the SPLIT function as per the documentation - String Functions
Vertica is listed as partially supported, so i wonder if it's a version issue?
I see you're doing a split within a split - what happens if you try and use one split only - does it work?
Thank you Tom - i had gone through the document earlier - it says it's supported for a left side SPLIT. However, it is not recognizing the SPLIT function at all.
I did try doing a single SPLIT() and the result is same -> unknown function SPLIT called.
Could it be a driver mismatch issue? My Vertica DB is version 6.1 whereas my driver version is 5.0. When I connect to Vertica, I do receive a message mentioning that not all functionalities are supported by this driver, but it doesn't mention String functions. Screenshot below:
I would start by trying to update the driver.
It could also be a restriction of version 6.1 versus the latest version of Vertica.
If the new driver doesn't fix it, I would open a ticket with Tableau Support.