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Using table indexes allows you to find information within your database faster and more efficiently. The two indexes most commonly used in databases are unique and non-unique. To ensure you’re using the indexes correctly, it’s important to know the difference between the two types of indexes and how to use them in your design. 

What is a Table Index? 

A table index is a method used to sort through information within a database. It functions in the same way as an index in a book does. You look at the index, find what information you need and go directly to it. Easy! 

Table indexes are usually made with one column in a table, but they can also have more than one column. Once your index is established, you can use queries to search for information. 

If your database is small, you might not miss having an index. But as your database grows, you’ll likely need one to speed up data retrieval. 

Unique vs Non-Unique Indexes 

The two most common indexes are unique and non-unique. A unique index ensures that the values in the index key columns are unique. It also guarantees that no duplicate values are inserted into the columns.

A non-unique index is when the indexed column has duplicate values. Generally speaking, you’ll use this type of index when linking or joining a table to a second table to return multiple results. 

When to Use Indexes 

Indexes give you quick access to the information you need in your database without having to look through every item. Unfortunately, they do come with a cost to performance. This is why you don’t want to overdo it and index each and every column. Instead, it’s best to use indexes on columns that are referenced in your queries. 

Let’s cover some pros and cons to using indexes in your database.


  • See better performance when using them in queries 
  • Easily retrieve the data you need – great for large databases 
  • Use them for sorting and avoid a post-fetch-sort operation 
  • Get uniquely identifiable records with a unique index 


  • Decreased performance on inserts, updates and deletes
  • Stored on disks with the potential to take up unnecessary space 

Bottom line: Only create indexes when you really need them. 

Arkware’s database experts can help you identify where to use table indexes and how to establish them. Contact us today for all of your questions and concerns, or let us build an efficient database that contains the right amount of table indexes.