A Deep Dive in How Slow SELECT * Is

Explore the intricacies of database performance in this 39-minute video that delves into the question of why SELECT * queries can be slow and costly. Learn about database page layout, how SELECT operations work, and the factors that contribute to query performance. Discover why index-only scans may not be possible with SELECT * queries, and understand the impact of deserialization costs. Examine the concept of inline and out-of-line columns, and how they affect query execution. Investigate the network costs associated with retrieving large amounts of data, and the client-side deserialization process. Gain valuable insights into database engineering and optimization techniques to improve query performance in row-store database engines.

Intro
Database Page Layout
How SELECT Works
No Index-Only Scans
Deserialization Cost
Not All Columns are Inline
Network Cost
Client Deserialization