ORA-34178
(MXCHGDCL02) workspace object cannot be changed to NOHASH. Only an object that was originally defined as NOHASH can be changed back to NOHASH.
Cause
NOHASH in the original definition created structures required to convert back to NOHASH later on.
Action
This is a rarely used feature. Performance should be thoroughly tested before the application is released for regular use.