Index Scan
Index Scan is a database query execution technique where the database engine uses an index to efficiently locate and retrieve rows from a table. It involves scanning the index structure (e.g., B-tree, hash) to find matching entries, then fetching the corresponding data from the table, often improving performance for selective queries. This contrasts with a full table scan, which reads all rows sequentially.
Developers should understand Index Scan to optimize database queries, as it's crucial for speeding up searches, joins, and filtering operations in large datasets, especially when queries involve indexed columns. It's used in scenarios like looking up specific records by primary key, range queries, or sorted retrievals, reducing I/O and CPU usage compared to scanning entire tables.