Difference between internal sorting and external sorting

7 Feb 2025 | 2 min read

In this article, we will learn about the differences between internal sorting and external sorting in detail. Sorting is a technique used for arranging the data in ascending or descending order. The main purpose of sorting technique is to comparison and interchanging position of elements. There are mainly two board classifications of sorting algorithms in data structures and each algorithm has a different sorting complexity.

Internal Sorting: In this type of sorting data is arranged in any order in computer main memory. i.e. RAM
External sorting: In this type of sorting data is arranged in any order in secondary storage device such as hard disk etc.

Difference between internal sorting and external sorting

Below are the tabulated differences between internal sorting and external sorting.

Sr. No	Internal sorting	External sorting
1.	Internal sorting occurs in the computer's main memory.	External sorting is mainly done with additional external memory such as magnetic tape or hard disk
2.	Internal sorting methods are applied to small collections of data.	These methods are applied only when the number of data elements is to be sorted is very large.
3.	It takes very smaller inputs for arranging the data.	External sorting can take larger inputs.
4.	In internal sorting, the collection of data should be sorted into small enough because the sorting can be done in main memory.	This type of sorting mostly uses a hierarchical merging strategy, and requires auxiliary storage.
5.	In this type of sorting, for sorting large datasets it may be necessary to keep only a small portion of the data in memory at a time.	In this type of sorting, small chunks of data enough to fit into main memory are read, sorted, and written to a temporary file.
6.	The various examples of internal sorting are: bubble sort selection sort internal sort quick sort bucket sort heap sort radix sort	The various Examples of external sorting are: merge sort Two-way merge sort. External Radix Sort
7.	Internal sorting does not use required additional resources.	External sorting uses additional resources.