---
title: "Explain the difference between a data block, an extent and a segment?"  
description: "Explain the difference between a data block, an extent and a segment?"  
author: "Sumit Kesarwani"  
published: 2014-01-31  
updated: 2020-09-23  
canonical: https://www.mindstick.com/interview/1910/explain-the-difference-between-a-data-block-an-extent-and-a-segment  
category: "mysql"  
tags: ["mysql"]  
reading_time: 1 minute  

---

# Explain the difference between a data block, an extent and a segment?

A data block is the smallest unit of logical storage for a database object. As objects grow they take chunks of additional storage that are composed of contiguous data blocks. These groupings of contiguous data blocks are called extents. All the extents that an object takes when grouped together are considered the segment of the database object.

## Answers

### Answer by Sumit Kesarwani

A data block is the smallest unit of logical storage for a database object. As objects grow they take chunks of additional storage that are composed of contiguous data blocks. These groupings of contiguous data blocks are called extents. All the extents that an object takes when grouped together are considered the segment of the database object.


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Original Source: https://www.mindstick.com/interview/1910/explain-the-difference-between-a-data-block-an-extent-and-a-segment

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