Which data structure improves the speed of data retrieval operations on a database table?

An index is a special data structure in databases designed specifically to improve the speed of data retrieval operations. It works similarly to an index in a book, allowing the database management system (DBMS) to quickly locate rows in a table without having to scan each row sequentially.

When you create an index on a specific column or set of columns in a database table, the DBMS builds a separate structure that maintains the values from those columns along with pointers to the corresponding rows. This enables the DBMS to perform searches and queries much faster, especially in large datasets. As a result, operations such as searching, sorting, and filtering become much more efficient.

Views, schemas, and triggers all serve different purposes: a view is a virtual table based on the result set of a query, a schema defines the structure and organization of database components, and a trigger is a set of instructions that execute automatically in response to certain events on a table. While these elements play important roles in database management, they do not directly enhance the speed of data retrieval operations like an index does.