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antirez
rax
C2017–2020
antirez / rax

rax

A radix tree implementation in ANSI C

4Distinct people
7Mentions
0Explicit recommenders
1.3KGitHub stars
REPOSITORY AT A GLANCE

What to know before exploring

What it is

A radix tree implementation in ANSI C

GitHub

Where it is used

No documented product use has been verified yet.

What people are saying

No recommendation phrase was found in the indexed comments.

No classified warning is attached to this page. Read the discussions before treating silence as approval.

Also in these discussions

No other repository is repeatedly linked in the same discussions.

This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 12:54:37 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year7 dated mentions

Observed mentions: 2017-04-06 11:49:19 UTC to 2020-10-26 09:00:36 UTC.

01232017-01-01 00:00:00 UTC to 2018-01-01 00:00:00 UTC (exclusive): 3 mentions; 2 submissions, 1 comments20172018-01-01 00:00:00 UTC to 2019-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments20182019-01-01 00:00:00 UTC to 2020-01-01 00:00:00 UTC (exclusive): 1 mentions; 0 submissions, 1 comments2020-01-01 00:00:00 UTC to 2021-01-01 00:00:00 UTC (exclusive): 2 mentions; 0 submissions, 2 comments2020

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges
UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
PeriodStart (UTC)End (exclusive, UTC)MentionsSubmissionsComments
20172017-01-01 00:00:00 UTC2018-01-01 00:00:00 UTC321
20182018-01-01 00:00:00 UTC2019-01-01 00:00:00 UTC101
20192019-01-01 00:00:00 UTC2020-01-01 00:00:00 UTC101
20202020-01-01 00:00:00 UTC2021-01-01 00:00:00 UTC202

What Hacker News says

7 sources
Hash tables for me were not just a data structure, I had some form of love for this way of organizing data. Can't forget the articles in the Dr. Dobb's issues about the new hashing schema, or how the new processors caches + access locality could change the game and so forth. But at this point, in 2018, I believe that hash tables should be rarely used. Take Redis for instance. I used an hash table to start. Very early in the project I discovered that people were going to use it to store large amounts of data and rehashing times were a too big price to pay, so let's switch to an incremental rehashing schema, with all the complexity. Then there was to implement some form of iteration (see the Redis *SCAN family of commands). So let's fight against the complexity of an incrementally rehashing hash table in the context of a stateless cursor it
Read the rest
erator. and so forth. Basically a decent implementation of hash tables end being slower and more complex to handle than a good radix tree implementation (not to implement, radix trees when full featured are a nightmare to get right, if you have a stateful iterator). So once you implement a good radix tree (check for instance the "rax.c" file inside Redis source code, or simply https://github.com/antirez/rax), you start to see that, hey! you have all the advantages of an hash table, but it's faster, the key space is sorted, you can iterate it in many ways, and the memory usage is much smaller. So I'm not sure at this point, other than "the simplest dictionary data structure I can implement just recalling from memory", if there are great applications for in-memory hash tables as data structures. They are perhaps starting to be more interesting for disk applications. For all my new projects I imagine myself just copying rax.[ch] and use it, unless there is some very odd reason why an hash table will be preferable.
In Dynamic Hash Tables (1988) [pdf]

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