Mediaspace scheduled maintenance: Aug 25, 2026 07:00 - 12:00 AM. During this time, videos will be temporarily unavailable. Check status updates.

Lecture

Query Optimization

In course

CS-322: Introduction to database systems

This course provides a deep understanding of the concepts behind data management systems. It covers fundamental data management topics such as system architecture, data models, query processing and optimization, database design, storage organization, and t ...

Description

This lecture covers the process of query optimization, starting from logical query plans to physical query plans. It explains the steps involved in query transformation, select-project-join optimization, and query rewriting. The lecture also delves into the estimation of costs for different query plans and the importance of statistics and catalogs in the optimization process.

This video is available exclusively on Mediaspace for a restricted audience. Please log in to MediaSpace to access it if you have the necessary permissions.

Watch on Mediaspace

Instructors (3)

Christoph Koch

Angelos Christos Anadiotis

Anastasia Ailamaki

Official source

Ontological neighbourhood

Computer engineering

Databases: Relational databases

Related concepts (32)

Query optimization

Query optimization is a feature of many relational database management systems and other databases such as NoSQL and graph databases. The query optimizer attempts to determine the most efficient way to execute a given query by considering the possible query plans. Generally, the query optimizer cannot be accessed directly by users: once queries are submitted to the database server, and parsed by the parser, they are then passed to the query optimizer where optimization occurs.

Join (SQL)

A join clause in the Structured Query Language (SQL) combines columns from one or more tables into a new table. The operation corresponds to a join operation in relational algebra. Informally, a join stitches two tables and puts on the same row records with matching fields : INNER, LEFT OUTER, RIGHT OUTER, FULL OUTER and CROSS. To explain join types, the rest of this article uses the following tables: Department.DepartmentID is the primary key of the Department table, whereas Employee.DepartmentID is a foreign key.

Relational algebra

In database theory, relational algebra is a theory that uses algebraic structures for modeling data, and defining queries on it with a well founded semantics. The theory was introduced by Edgar F. Codd. The main application of relational algebra is to provide a theoretical foundation for relational databases, particularly query languages for such databases, chief among which is SQL. Relational databases store tabular data represented as relations. Queries over relational databases often likewise return tabular data represented as relations.

Query plan

A query plan (or query execution plan) is a sequence of steps used to access data in a SQL relational database management system. This is a specific case of the relational model concept of access plans. Since SQL is declarative, there are typically many alternative ways to execute a given query, with widely varying performance. When a query is submitted to the database, the query optimizer evaluates some of the different, correct possible plans for executing the query and returns what it considers the best option.

Presentation slide

A slide is a single page of a presentation. Collectively, a group of slides may be known as a slide deck. A slide show is an exposition of a series of slides or images in an electronic device or in a projection screen. Before the advent of the personal computer, a presentation slide could be a 35 mm slide viewed with a slide projector or a transparency viewed with an overhead projector. In the digital age, a slide most commonly refers to a single page developed using a presentation program such as MS PowerPoint, Apple Keynote, Google Slides, Apache OpenOffice or LibreOffice.

Related lectures (55)

Physics-inspired Computing and Neuromorphic Algorithms

Explores physics-inspired computing, analog computing, optical computing, and the potential of spin waves for physics-based computing.

Scanning Electron Microscopy: Signals and Detectors

Covers the principles of Scanning Electron Microscopy, including SEM signals, detectors, and energy spectrum of electrons, as well as the efficiency of X-ray generation.

Understanding Noise in Electrical Systems

Explores noise sources, Fluctuation-Dissipation Theorem, amplifier noise, interference effects, and quantization error in electrical systems.

Noise Reduction Techniques

Explores noise reduction techniques in electrical systems, covering concepts like Fourier transform, impedance matching, and dithering.

Vision-Language-Action Models: Training and Applications