Write-ahead logging and the ARIES crash recovery algorithm

A central tenet of databases is that any committed data survives a crash or a failure. Write-ahead logging is a fundamental primitive that ensures all changes to data are first written safely to stable storage before being applied. Coupling that with some careful use of sequence numbers and we can guarantee that changes made to a database can survive system crashes. Motivation Let’s start with a simple transaction T1 that reads object A, and updates the value for A with a write....

August 26, 2022 · 21 min · Kevin Sookocheff

Paper Review: Combining Systems and Databases: A Search Engine Retrospective

Title and Author of Paper Combining Systems and Databases: A Search Engine Retrospective. Eric A. Brewer. Summary Search engines manage data and respond to queries, which provides some similarities to databases. However, search engines are really an application-specific system built to handle large datasets. This system can leverage databases, or not, depending on the system goals. This paper describes a search engine design that leverages the ideas and vocabulary of the database community....

March 27, 2017 · 6 min · Kevin Sookocheff

Paper Review: The Volcano Optimizer Generator: Extensibility and Efficient Search

Title and Author of Paper The Volcano Optimizer Generator: Extensibility and Efficient Search. Goetz Graefe and William J. McKenna. Summary The query optimizer’s job is to take user input in the form of SQL and generate a cost-efficient plan for satisfying that query using the underlying physical layout of the database. This paper describes Volcano, a system for taking a data model, logical algebra, physical algebra, and optimization rules and translating them into optimizer source code....

October 11, 2016 · 3 min · Kevin Sookocheff

Paper Review: What Goes Around Comes Around

Title and Author of Paper What Goes Around Comes Around. Joseph M. Hellerstein and Michael Stonebraker. Summary What Goes Around Comes Around summarizes several methods for modelling data within a database system. Each data model is described and the benefits and drawbacks listed as lessons learned from research into that model. The authors clearly present their opinions on each model and help readers unfamiliar with past modelling attempts understand the history of this area of research....

January 27, 2016 · 3 min · Kevin Sookocheff