Indexed Sequential Access Method is a technique for creating, preserving, and altering computer data files so that entries can be accessed sequentially or randomly using one or more keys. To achieve quick retrieval of the required file records in the indexed files, key field indexes are maintained.
In this article, we will dive deeper into the indexed sequential access method (ISAM) according to the GATE Syllabus for (Computer Science Engineering) CSE. Keep reading ahead to learn more.
Table of Contents
What is the Indexed sequential access method (ISAM)?
ISAM (Indexed sequential access method) is an advanced sequential file organization method. In this case, records are stored in the file with the help of the primary key. For each primary key, an index value is created and mapped to the record. This index contains the address of the record in the file.
If a record has to be obtained based on its index value, the data block’s address is retrieved, and the record is retrieved from memory.
Pros of ISAM
- Because each record consists of the address of its data block in this manner, finding a record in a large database is rapid and simple.
- Range retrieval and partial record retrieval are both supported by this approach. We may obtain data for a specific range of values because the index is based on primary key values. Similarly, the partial value can be simply found, for example, in a student’s name that begins with the letter ‘JA’.
Cons of ISAM
- This approach necessitates additional disc space to hold the index value.
- When new records are added, these files must be reconstructed in order to keep the sequence.
- When a record is erased, the space it occupied must be freed up. Otherwise, the database’s performance will suffer.
Keep learning and stay tuned to get the latest updates on GATE Exam along with GATE Eligibility Criteria, GATE 2023, GATE Admit Card, GATE Syllabus, GATE Previous Year Question Paper, and more.
Also Explore,
Comments