Top all-time · #4009
Justin Jaffray
Personal blog · justinjaffray.com · on HN as foldUdataprogramming
Justin Jaffray's personal blog at justinjaffray.com covers data and programming. Since 2016, 19 different Hacker News readers have linked it 40 times, most often “A Charming Algorithm for Count-Distinct”. The last post was in 2023, but the archive is still widely read.
Too few sampled comments (4) to say how often HN recommends it.?
Why HN links it
HN readers link Justin Jaffray's blog for writing on database query engines and worst-case optimal joins. Commenters point to a push vs. pull query engines post and a WCOJ introduction.
Summarised by Claude from a sample of 4 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Most-linked posts?
- A Charming Algorithm for Count-Distinct4 people · 5 mentions · first linked 2023-01-26
- Query Engines: Push vs. Pull (2021)3 people · 3 mentions · first linked 2023-07-31
- Join: The Projection2 people · 2 mentions · first linked 2022-06-13
- Durability and Redo Logging2 people · 2 mentions · first linked 2022-01-24
- What Is a Query Optimizer For?2 people · 2 mentions · first linked 2020-02-11
- /a-gentle-ish-introduction-to-worst-case-optimal-joins/2 people · 2 mentions · first linked 2022-07-28
- Query Engines: Push vs. Pull2 people · 2 mentions · first linked 2021-04-26
What Hacker News says?
The intuition is that if your join is a triangle you might be forced to join every relation only to discover that the result is empty on the last join, which requires m^n intermediary results, where m is the size of the relations and n is the number of relations. A WCO join algorithm will figure out quite quickly that the output is empty and is in practice much more dependent on the actual output size, than the size…
Comment linking /a-gentle-ish-introduction-to-worst-case-optimal-joins/
on “SQLite Internals: Pages and B-trees”Submitted Query Engines: Push vs. Pull as a story · 148 points
HN discussionI enjoyed this post on pull/push based query engines - its examples were wonderfully simple. https://justinjaffray.com/query-engines-push-vs.-pull/
Comment linking /query-engines-push-vs.-pull/
on “Ask HN: Share your favorite software blog posts of 2023”Submitted Query Engines: Push vs. Pull (2021) as a story · 102 points
HN discussionJustin also has a post on WCOJ that's really solid: https://justinjaffray.com/a-gentle-ish-introduction-to-worst...
Comment linking /a-gentle-ish-introduction-to-worst-case-optimal-joins
on “Joins 13 Ways”Submitted Timely Dataflow and Total Order as a story · 97 points
HN discussionexcellent intro to worst case optimal joins: https://justinjaffray.com/a-gentle-ish-introduction-to-worst...
Comment linking /a-gentle-ish-introduction-to-worst-case-optimal-joins/
on “Recent advances in computer science since 2010?”Submitted A gentle-ish introduction to worst-case optimal joins as a story · 92 points
HN discussionSubmitted What Write Skew Looks Like as a story · 89 points
HN discussionSubmitted Durability and Redo Logging as a story · 28 points
HN discussionSubmitted A Charming Algorithm for Count-Distinct as a story · 24 points
HN discussionSubmitted Joins 13 Ways as a story · 18 points
HN discussionSubmitted A Gentle(-Ish) Introduction to Worst-Case Optimal Joins as a story · 9 points
HN discussionSubmitted Compaction as a story · 8 points
HN discussionSubmitted Deduplicating Decklists as a story · 7 points
HN discussionSubmitted Understanding Cost Models as a story · 7 points
HN discussionSubmitted What Does Write Skew Look Like? as a story · 6 points
HN discussionSubmitted A Charming Algorithm for Count-Distinct as a story · 5 points
HN discussionSubmitted Join: The Projection as a story · 4 points
HN discussionSubmitted Query Engines: Push vs. Pull as a story · 4 points
HN discussionSubmitted Query Engines: Push vs. Pull as a story · 4 points
HN discussionSubmitted Reflections on Stacking Stacks as a story · 4 points
HN discussionSubmitted Understanding Cost Models (2020) as a story · 3 points
HN discussionSubmitted A Charming Algorithm for Count-Distinct as a story · 3 points
HN discussionSubmitted A Proof of Correctness for CASPaxos as a story · 3 points
HN discussionSubmitted Making a Tool-Assisted Speedrun for PICO-8 as a story · 3 points
HN discussionSubmitted Null Bitmap Zine #1 [pdf] as a story · 2 points
HN discussionSubmitted Two-Phase Commit Three Ways as a story · 2 points
HN discussionSubmitted Joins 13 Ways as a story · 2 points
HN discussionSubmitted A Charming Algorithm for Count-Distinct as a story · 2 points
HN discussion
