Lecture
This lecture covers the iterator model in query processing for database systems, where operators are arranged in a tree structure, and data flows from leaves to the root. It explains the processing model of a DBMS, focusing on the extreme tuple-at-a-time execution. The lecture details the iterator model's implementation, including the common operator interface for composability and the interpreted expression evaluation. It also discusses the challenges of tuple-at-a-time processing, such as multiple function calls and the need to cover various table types and queries.