BTW, if a file has been renamed and edited, you're out of luck, because the hash-comparison will fail even if the meta-data matches.
You don't need to set hashing by default for all files, by the way - the Rename/Move detection functionality will do it behind the scenes as & when required anyway (if it can, as mentioned)
You don't need to set hashing by default for all files, by the way - the Rename/Move detection functionality will do it behind the scenes as & when required anyway (if it can, as mentioned)