data structures using table sequential file organization features advantages disadvantages records are written in the order in which they are entered records are read and written sequentially deletion or updation of one or more records calls for replacing the original file with new file that contains the desired changes records have the same size and the same field format records are sorted on key value generally used for report generation or sequential reading simple and easy to handle no extra overheads involved sequential files can be stored on magnetic disks as well as magnetic tapes well suited for batchoriented applications records can be read only th sequentially if record has to be readthen all the - records must be read does not support update operation new file has to be created and the original file has to be replaced with the new file that contains the desired changes cannot be used for interactive applications relative file organization relative file organization provides an effective way to access individual records directly in relative file organizationrecords are ordered by their relative key it means the record number represents the location of the record relative to the beginning of the file the record numbers range from to - where is the number of records in the file for examplethe record with record number is the first record in the file the records in relative file are of fixed length thereforein relative filesrecords are organized in ascending relative record number relative file can be thought of as single dimension table stored on diskin which the relative record number is the index into the table relative files can be used for both random as well as sequential access for sequential accessrecords are simply read one after another relative files provide support for only one keythat isthe relative record number this key must be numeric and must take value between and the current highest relative record number - this means that enough space must be allocated for the file to contain the records with relative record numbers between and the highest record number - for exampleif the highest relative record number is , then space must be allocated to store , records in the file figure shows schematic representation of relative file which has been allocated enough space to store records although it has space to accommodate recordsnot all the locations are occupied the locations marked as free are yet to store records in them thereforeevery location in the table either stores relative record records stored record or is marked as free in memory number relative file organization provides random access by directly record jumping to the record which has to be accessed if the records record are of fixed length and we know the base address of the file and the length of the recordthen any record can be accessed using free the following formula free record free record figure relative file organization address of ith record base_address ( - record_length note that the base address of the file refers to the starting address of the file we took - in the formula because record numbers start from rather than consider the base address of file is and each record occupies bytesthen the address of the th record can be given