Question

Primary indexes, secondary indexes and cluster indexes are all types of

• A. unordered indexes.
• B. ordered indexes.
• C. linear indexes.
• D. relative search indexes.

Answer 1

The correct option is B ordered indexes.

Primary indexes, secondary indexes and cluster indexes are all types of $\text{ordered indexes}$.

$\text{Primary indexes}$:If the index is created on the primary key of the table then it is called as Primary Indexing. These primary key are kept in sorted form which helps in performance of the transactions. The primary indexing is of two types – Dense Index and Sparse Index.

$\text{Secondary indexes}$: In these method, another level of indexing is introduced to reduce the (index, address) mapping size. That means initially huge range for the columns are selected so that first level of mapping size is small.

$\text{Cluster indexes}$: In some cases, the index is created on non-primary key columns which may not be unique for each record. In such cases, in order to identify the records faster, we will group two or more columns together to get the unique values and create index out of them. This method is known as clustering index.