Indexed Sequential Access Method (ISAM):
This method combines both the feature of sequential and random organization. Records are accessed by using an index or a table. The index stores the address of each record corresponding to a key number of the record.
The records within the file are stored sequentially but directly accessed to individual records.
An indexed sequential access method (ISAM) consists of
- The main file storage
- A table to maintain the index
Advantages:
- It combines both sequential and direct
- Suitable for sequential access and random access
- Provides quick access to records
Disadvantage:
- it uses special software and is expensive
- extra time is taken to maintain index
- extra storage for index files
- expensive hardware is required
