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Database index

Written by Editorial staff | Jan 24, 2023 10:16:33 AM

What is database index?

A database index is a data structure that improves the speed of data retrieval on a database table. Basically, an index allows a database to quickly find and retrieve specific rows of data from a table based on the values of one or more columns in the rows, in the same way that a table of contents in a book can help you find specific information in the book. 


This can greatly improve the performance of database queries, especially when working with large amounts of data. For example, if you have a database table with millions of rows of data and you want to find all rows with a specific value in a specific column, using a database index can significantly speed up the query by allowing the database to find the relevant rows without having to scan the entire table. However, they come with some costs, as they may require additional storage space and may slow down insert and update operations. As a result, it is important to carefully consider which columns to index and how many indexes to create in a database.


There are several types of indexes that can be set up within a database, including:

  • Clustered indexes: 
    These indexes rearrange the rows within a table based on the indexed column(s). This way, the data is physically stored in a specific order. There can only be one clustered index per table.

  • Non-clustered indexes: 
    These indexes save the data in a separate structure from the table instead of rearranging the rows. This allows for faster lookups, but it can be slower for insert and update operations. A table can have multiple non-clustered indexes.

  • Unique indexes:
    These indexes enforce a uniqueness constraint on the indexed column(s), which ensures that there are no rows in the table that have the same values in those columns. 

Cegal and database index

Cegal has a lot of expertise and experience with a wide range of database technologies including: Oracle, MS SQL, PostgreSQL, MySQL, MongoDB and NoSQL.

Within these areas, we provide both Managed Services and consultancy services. We have developed a safe and simple solution to monitor your database systems and maintain them proactively. We thus ensure a stable platform via ongoing assistance, monitoring, operational services and operation. We also help with advice in the form of finding the right solution based on our customers’ systems and needs.


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