How to index data in the database for search?

- Indexing is an important feature of MySQL. It supports different type of indexes like primary key index, unique index, normal index and full-text index. Indexes help to speed up the retrieval of data from MySQL database server.

- Drupal's search engine indexes the text content of the nodes on your site

- The search engine indexes at intervals you choose by setting "cron runs."  Cron is not a part of Drupal. It's a scheduler that resides on your server and runs tasks at intervals, which you specify.