When records are arranged physically in a certain order, the file is said to be a sequential file.
-when the file is updated, it is necessary to go through the entire file
-sequential organization would make sense when many records need to be read or modified.
-all records have the same size and the same field format and the records are sorted in the file according to the content of a field called key.
-the files can be saved both on a disk or on a tape.
-disadvantage : Adding or deleting records become physical.
Records in a file can be accessed directly without reference to the other records in the file
-provides a much faster access.
-the records can be scattered over the disk space in any order.
The rows are stored either sequentially or non-sequentially
-an index is created that allows software to locate individual rows.
Index – a table used to determine the location of rows in a file that satisfy some condition.
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