Differences between Nested Loop Join and Merge Join

 Below are the difference between them

Sno	Feature	Nested Loop Join	Merge Join
1	Use Case	Small datasets or highly selective joins	Large datasets with ordered data
2	Data Requirements	No specific data order required	Both inputs must be sorted on the join column
3	Execution Strategy	Iteratively checks each row in one table against rows in the other table	Matches rows from two sorted inputs sequentially
4	Performance	Efficient for small datasets or when one input is small and indexed	More efficient for large, pre-sorted datasets
5	Index Dependency	May benefit from indexes but doesn’t require them	Best suited when indexes or ordered data exists
6	Complexity	O(N*M) complexity (less efficient for large datasets)	O(N + M) complexity (efficient with sorted data)