Error "ORA-01406: fetched column value was truncated" Creating Extract When Using Custom SQL

Published: 23 Jun 2014
Last Modified Date: 10 Dec 2018


When you are using custom SQL in your data source connection and you try to create an extract , the following error might occur:
Oracle database error 1406: ORA-01406: fetched column value was truncated
Unable to create extract

When connecting to the Oracle data base and creating an extract without custom SQL, the extract completes successfully.


  • Tableau Desktop
  • Oracle
  • Custom SQL


As a workaround, rather than using Custom SQL, use the same code to create a materialized view directly in the database. 

Additional Information

Materialized Views

A materialized view is a “select query” performed on the data source and the result set is stored as a table in the database. The materialized view can be kept in sync with database updates.
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