How to: Dense Index
In a dense index, an index record is created for every row of the table. Records can be located directly as each record of the index holds the search key value and the pointer to the actual record.

![dense-index](https://raw.githubusercontent.com/karanpratapsingh/portfolio/master/public/static/courses/system-design/chapter-II/indexes/dense-index.png)

Dense indexes require more maintenance than sparse indexes at write-time. Since every row must have an entry, the database must maintain the index on inserts, updates, and deletes. Having an entry for every row also means that dense indexes will require more memory. The benefit of a dense index is that values can be quickly found with just a binary search. Dense indexes also do not impose any ordering requirements on the data.