Aiven has released PostgreSQL 18, which features significant performance improvements and new functionalities like asynchronous I/O, enhanced JOIN and GROUP BY operations, and parallel GIN index creation. This version allows more flexibility in schema evolution and smarter indexing with skip scans. Users can try PostgreSQL 18 with a free trial at Aiven.

PostgreSQL's Index Only Scan enhances query performance by allowing data retrieval without accessing the table heap, thus eliminating unnecessary delays. It requires specific index types and query conditions to function effectively, and the concept of a covering index, which includes fields in the index, further optimizes this process. Understanding these features is crucial for backend developers working with PostgreSQL databases.