Why Databases Choose B+ Trees Over Hash Tables and B-Trees
When you create an index on a database table, have you ever wondered what data structure actually powers it? The answer is almost always a B+ tree. Not a hash table. Not a regular B-tree. Not a binary search tree. B+ trees have been the default index structure in nearly every major relational database for over five decades—MySQL, PostgreSQL, Oracle, SQL Server, and SQLite all use them. This isn’t coincidence or legacy inertia. It’s the result of fundamental trade-offs between disk I/O patterns, range query efficiency, and storage utilization. ...