can you tell if they are temp tables? if the users are leveraging context filters, then this is one way that temp tables will be created.
Tableau may be creating and deleting temporary (Oracle) tables in the database so it's not truncate of the table you are querying which you are seeing. Check whether the user account you are using has these permissions. I think Tableau will use temporary tables on the database if it can but if the user doesn't have these permissions then it won't.
Any user can create and truncate tables in the temp area in the databases. I even observed this in greenplum,postgresql So it even applies for oracle
In Oracle the user needs CREATE TABLE privilege, if they don't have this they can't create tables anywhere. The user doesn't need this to use Tableau.
Thanks for your responses guys. The error code in the temp tables created shows that the actions actually failed. So, the temp tables did not get created.
If the user had create permissions, this would create temp tables. Would this help in increasing the performance on the tableau side? I'm assuming that tableau creates temp tables for better query execution and hence better performance.
I spoke to our Oracle dba (sits about 3 meters from me) and he said Oracle can create kinda-sorta temp tables as part of its internal processing of a query and specific CREATE TABLE privileges aren't necessary.
So, yes, this is normal and fine. If you can have the source db do the work for you then that's generally good as it's optimized and configured to do it and do it quickly!