What isISAM

ISAM, short for Indexed Sequential Access Method, is an advancement of the sequential file organization method used for efficient data management. In this file system, record data is stored sequentially, but with an additional index field. This index field is used to map the address of a data block in memory where the primary key of the record is stored.

The ISAM method is specifically designed to retrieve records stored in a particular order using index-based searching. IBM developed this file management technology, which has now been replaced by the Virtual Storage Access Method.

Compared to other database systems, ISAM has small indexes which simplify and speed up searching. Additionally, modifying data in one record doesn’t require changes in other records or indexes, which saves time and effort. This technique provides faster data access and permits quick retrieval of specific records using the index field.

However, the ISAM method requires a specific record key in the indexed record, unlike other sequential methods.


What is ISAM used for?

ISAM is a file organization method used for sorting through and accessing data quickly. This file management system has been superseded by VSAM.

What is the difference between ISAM and VSAM?

The ISAM method is an indexed sequential access method that uses indexes to quickly find records stored in a specific order. In contrast, VSAM is a virtual storage access method, which is used to manage data on disk efficiently. VSAM can provide better support for batch processing than ISAM.

Is ISAM still used today?

The ISAM method has been superseded by more advanced file management technologies such as VSAM, but it is still used in some legacy systems.


ISAM is an indexed sequential access method that provides a set of advanced techniques applied to the sequential file organization method. It is capable of managing data effectively and provides faster access to specific records with an index field. Even though it has been superseded by modern file management systems, it still has relevance in legacy systems.

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