You should use the built-in Redshift connection rather than the other database connection.
I've never seen this problem. You will probably need to contact support and have them review the logs.
Thanks for your reply Dan.
But i am advised to use the ODBC connection as it is a role based access for me to redshift database. Do u have any other clue about what might cause this issue?
Unfortunately Tableau doesn't yet support IAM based connectivity to Redshift.
Reviewing the logs would help. I recommend sending them to support.
You should also try upgrading to the latest Redshift ODBC driver. We've definitely seen some problems that they've fixed in newer versions.
I looked through reports from other customers and I did find reports of an issue about case-matching of column names. Redshift has a setting "describe_field_name_in_uppercase". There are also settings in Tableau's TDC files (Tableau Capability Customizations Reference - Tableau) to control whether Tableau matches columns in a case-sensitive ways. It's quite likely that changing this setting on the Redshift or Tableau end will help.