Can you run the custom SQL against the real Data-source and check (out of Tableau)?
Difficult to tell like this.
If I run it in SSMS I do get a result.
This used to happen to me when I was trying to blend a SQL Server table with a Spatial file. This was however erratic, then I JOINed those two sources and never had a problem.
- Does the live connection work?
- Try to publish it to a Server using Live connection and when prompted to create extract, proceed creating one. See if it works.
- Also, sometimes I used to close the workbook, re-open it, almost immediately create extract and that used to work.
- Another thing you could try as soon as you open the workbook start performance recording, run the extract, when it fails, stop the performance recording and see what it shows. Also Tableau logs are good place to troubleshoot.
I don't think it has anything to do with custom sql and probably not the type of server. I get the same problem when pull reasonably large tables (i.e. many fields per table not so much on rows) and more than two tables joining.
Sometimes the issue is I just have to wait for the import to start picking up. If you let it sit for a while -- sometimes a long while depending on the strength of your connection and the size of your number of row and especially the number of columns -- it usually will pick up.