1 of 1 people found this helpful
"Convert to Custom SQL" is a one-way operation.
No way to roll back other than using the Back button
while the Tableau Desktop session is still open.
Besides, the "converted" Custom SQL datasource
is not the same thing as the original one (before the conversion).
Using the original table objects combined into the datasource schema,
Tableau would parse its' metadata and generate more efficient SQL code.
With Custom SQL object(s), Tableau simply wrap its' own code around them
(each Custom SQL to become a sub-SELECT inside a Tableau-generated query).