Indexing is a way to optimize the performance of a database by minimizing the number of disk accesses required when a query is processed. It is a data structure technique which is used to quickly locate and access the data in a database.
Indexes are created using a few database columns.
- The first column is the Search key that contains a copy of the primary key or candidate key of the table. These values are stored in sorted order so that the corresponding data can be accessed quickly.
- Note: The data may or may not be stored in sorted order.
- The second column is the Data Reference or Pointer which contains a set of pointers holding the address of the disk block where that particular key value can be found.
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