Question

Explain sequential file and indexed sequential file

Answer 1

Sequential Files

Sequential files are called as QSAM files. Data is entered in entry sequential order. Duplicate data is allowed. Data is not in sorted order. Delete is not applicable. Access is slow.Key is not available. Data is stored on tape/disk. File modes. INPUT. OUTPUT. I-O. EXTEND. Frequently used files.

Indexed Files

Data is entered in key sequential order. Duplicate data is not allowed.Data is in sorted order based on key. Delete is applicable. Access is faster. Key is available. Key is user defined. Key is part of a record. Data is stored on disk only. File modes. INPUT. OUTPUT. I-O. Rarely used files. Indexed files are also called as VSAM files.