String Fields In Database Have More Than 255 Characters Are Truncated When Connecting To Databricks In Tableau Desktop

Issue

When connecting to Databricks in Tableau Desktop, if the string fields has more than 255 characters, they will be truncated to 255 characters.

Environment

Tableau Desktop
Databricks Connector
SparkSQL ODBC driver

Resolution

1. Use TDC file to increase the String Column Length:

<?xml version='1.0' encoding='utf-8' ?>
<connection-customization class='databricks' enabled='true' version='10.4'>
<vendor name='databricks'/>
<driver name='databricks'/>
<customizations>
<customization name='odbc-connect-string-extras' value='DefaultStringColumnLength=500' />
</customizations>
</connection-customization>

2. Change the default value from DSN and then use ODBC connector:
User-added image

Cause

The truncation of the 'string' field to 255 characters is caused by a default String Column Length within SparkSQL ODBC driver.

Additional Information

Default StringColumnLength - Default Value is 255
https://www.simba.com/products/Spark/doc/v2/ODBC_InstallGuide/mac/content/odbc/options/defaultstringcolumnlength.htm

Simba Spark ODBC Driver with SQL Connector (scroll to "Default String Column Length" section)
https://docs.datafabric.hpe.com/60/attachments/JDBC_ODBC_drivers/SparkODBCInstallandConfigurationGuide.pdf

Connecting to Databricks
https://docs.databricks.com/integrations/bi/tableau.html