Update Rows using Write Data In-DB tool

[SSteckler]

I am trying to update existing rows in a database table.  I can do it by streaming my data out and using the Output Data tool (so I know I have the right permissions, etc), but I can't figure out how to use the Write Data In-DB tool to do the same thing.  I don't even see the Update Rows option in the Output Mode dropdown menu (I have updated to version 2019.1).  I've checked that the field names, and number of fields all match.  What  am I missing?

[philipc]

Limitations: Update/Delete is currently only supported for SQL Server ODBC connections. Any updates on this limitation? I was trying to update a column in a  postgress database table. Failed with this error message  "Primary key required for update option"