Understanding Database Transactions and ACID Rules

What is this page about?

A deep explainer of database transactions and the ACID properties, defining a transaction and why transactions exist, then working through atomicity (all-or-nothing via write-ahead logging, undo/redo logs, savepoints), consistency (preserving invariants), isolation (concurrency problems, isolation levels, PostgreSQL's MVCC, locking, and deadlock handling), and durability (WAL, checkpoints, crash recovery). It also covers optimistic versus pessimistic concurrency, distributed transactions and two-phase commit, the saga pattern, the CAP theorem and BASE, practical patterns, and performance considerations.

What has been corrected on this page?

Every accepted correction to this page is recorded with the exact change, so readers can see how the page improved over time.

1. 11 July 2026 · corrected by Emir Baycan

   Paper was authored by Gray, Lorie, Putzolu, and Traiger, not solely with Putzolu (and the name is Gianfranco, not Franco)

   Before

   co-authored with Franco Putzolu, at IBM's San Jose

   After

   co-authored with Raymond Lorie, Gianfranco Putzolu, and Irving Traiger, at IBM's San Jose

   Why: Verified live: body content already correctly lists all four co-authors (Gray, Lorie, Putzolu, Traiger) with the correct name Gianfranco Putzolu. FAQ, excerpt, meta_description, and seo_keywords contain no reference to this citation, so no residual fabrication anywhere on the post.

   View the full record →

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