To understand the importance of indexing, you need to understand what an index is and its purpose.

In a typical database, an index is an internal structure that is used to increase the speed of data retrieval. An index is a copy of selected data that can be searched very efficiently, which might also include a file-level disk block number or even a direct connection to the entire set of data it was copied from.

Although Splunk indexes are structured a bit differently than typical database indexes, the objective is basically the same. Splunk uses its indexes to facilitate flexibility in searching and to improve data retrieval speeds.