What is the role of the EXPLAIN command in SQL query analysis?

The EXPLAIN command in SQL is used to analyze the execution plan of a query by the database. It shows how the DBMS intends to execute the query: which indexes will be used, the order of table scans, types of joins, etc.

This helps to:

• Identify bottlenecks in queries.
• Understand why a query is slow.
• Optimize queries and database structure.

For example, in PostgreSQL:

EXPLAIN SELECT * FROM users WHERE age > 30;

The result will show what type of table scan will be used and which indexes are involved.

Thus, EXPLAIN is an important tool for diagnosing and optimizing SQL query performance.