Relative file organization
A relative file is an array of fixed-length slots and the records can be inserted in the first free slot found from the beginning of the file and at the end of the file or in a specified slot in the file. Relative files are habitually used when record number will access records directly. Since each of the slots in a relative file is the same size, SFS is able to calculate the position of a specific record (identified by record number) by multiplying the record number by the record slot size.
The records in a relative file is able to be composed of fixed or variable-length fields except the size of each slot in the file is that of the maximum record size (which is calculated from the record specification when a relative file is created). The records in a relative file are able to be updated or deleted in place. Any slots free when records are deleted are able to be reused by subsequent insertions.
The primary index or else a relative file are based on the relative slot number (RSN), which correspond to the number of the slot occupied by a record the first relative slot number in a file is slot number 0 and the highest slot number can't exceed the maximum number of records specified when the file was created and the RSN is a physical part of the user's data record in Contrast this with the ESN used in entry-sequenced files. While a relative file is created at least one field must be of type sfs_unsignedInt32. This field ought to be specified as the primary index