Should IDX8 files be missing the .idx portion?

Problem:

A customer used the "rebuild" command with its conversion options, to convert an IDX3 file into an IDX8 file.  [Strictly speaking the original file wasn't converted "in place", instead the rebuild command creates a new IDX8 file and populates it with the data from the original IDX3 file].

A common reason for converting an IDX3 to an IDX8 is so the file can safely grow to very large sizes (when used in conjunction with the FILEMAXSIZE file handler configuration option).

But the customer noticed that the new IDX8 file consisted of only one disk file instead of two.  IDX3 files have a data portion with a basename, and an indexed portion with an ".idx" extension, for example "CUSTDATA" and "CUSTDATA.idx".  But the new IDX8 file did not have an accompanying ".idx" portion.  Is this the intended behavior?

Resolution:

The answer is yes, IDX8 files are "monolithic", that is, they occupy just one inode (one disk file).  The data and the index are held together within the same disk file.  This is the intended behavior and does not indicate a problem.