Primary index: It works on unique indexes. The data should be unique and not null. Retrieve data from the database.

Clustered Index: It works on unique and non unique indexes. Retrieve data from the AOS.

The advantages of having a cluster index are as follows:

1. Search results are quicker when records are retrieved by the cluster index, especially if records are retrieved sequentially along the index.
2. Other indexes that use fields that are a part of the cluster index might use less data space.
3. Fewer files in the database; data is clustered in the same file as the CLUSTERING index. This REDUCES the space used on the disk and in the cache.
4. The disadvantages of having a cluster index are as follows:
5. It takes LONGER to UPDATE records (but only when the fields in the clustering index are changed).
6. More data space might be used for other indexes that use fields that are not part of the cluster index (if the clustering index is wider than approximately 20 characters).

Primary index: It works on unique indexes. The data should be unique and not null. Retrieve data from the database.

Clustered Index: It works on unique and non unique indexes. Retrieve data from the AOS.

The advantages of having a cluster index are as follows: