The filesystem that qdb uses for temporary storage must support POSIX file locking. File locking is required for database vacuuming.
The qdb utility checks its temporary storage as follows:
If all the above conditions are met, qdb sets the internal temporary storage to the location specified by the tempstore option. If any of the above conditions are not met, qdb logs errors to slog and fails to start up.
If all the above conditions are met, qdb sets the internal temporary storage to the value of TMPDIR. If any of the above conditions are not met, qdb logs errors to slog and fails to start up.