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Indexed Sequential Access Method

What Does Indexed Sequential Access Method Mean?

An Indexed Sequential Access Method (ISAM) is a file management technology developed by IBM and focused on fast retrieval of records which are maintained in the sort order with the help of an index. This file management system was succeeded by the virtual storage access method.


Techopedia Explains Indexed Sequential Access Method

When data are being stored in an Indexed Sequential Access Method, they are entered sequentially. Unlike other navigational databases, an Indexed Sequential Access Method had small indexes, making the search relatively faster. Data modification to the record did not require any changes to other records or indexes. The methodology focused on providing direct access to specific records with the help of indexes. The combination of this access and index helps in faster data access. Unlike other sequential methods, ISAM requires record keys in the indexed record to be specific.

There are many advantages related to ISAM. The method makes use of direct and sequential access to the data record. The method is not only easy to understand and implement, but also is also inexpensive. Searching for or locating a specific record in a large database is relatively easy with the help of this system. The Indexed Sequential Access Method also supports partial retrieval and range retrieval of records. There is more flexibility in terms of this technology.


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