April 11, 2026
When dumb-fast meets dont-do-it
Simplest Hash Functions
Dev touts 'dumb fast' hashes; commenters clap back, nitpick, and drop receipts
TLDR: A developer argued for ultra-simple, non-cryptographic hashing for safe, non-hostile data, sparking debate. Commenters split between “never in production,” “it depends on the use case,” and nitpicks about addition vs XOR, while others linked research and recommended proven options like djb2—because bad hashes can tank apps.
An opinionated post pitched ultra-cheap “hash” tricks—think adding numbers together and calling it a day—instead of heavyweight cryptographic stuff like SHA-256. The author jokes these would make a cryptographer scream, and the crowd certainly did. The top vibe: use these only if you’re 100% sure no one can mess with your input or you might accidentally invite a slowdown attack where everything piles into the same bucket. One purist snapped that anything colliding with what’s already in the table “shouldn’t be called a hash,” while another started a mini hardware war asking why addition would be cheaper than XOR—cue heated micro-nerd debates.
The pragmatists chimed in with “it depends on the job”—hashing a short word, a big block, or an integer are different sports. A few brought receipts: one linked an academic deep dive on tabulation methods here, another waved the classic, battle-tested djb2 as the “don’t reinvent the wheel” option. Meanwhile, jokesters latched onto the post’s cheeky lines about skipping every other word to “save electricity,” turning it into a meme about eco-friendly hashing. The drama: minimalism vs. safety, speed vs. sanity. The mood: curious but cautious, with a side of “please don’t ship this to production.”
Key Points
- •The article focuses on ultra-simple, non-cryptographic hash functions suitable for non-adversarial scenarios.
- •It presents rapidhash’s core (XOR, multiply, fold) as a minimal design but warns of collision risks and potential hash table degradation under malicious inputs.
- •For trusted inputs, it suggests extremely cheap hashes such as summing 32-bit words, and improving order sensitivity by adding a rotation step.
- •It notes that sampling or skipping parts of the input can further reduce hashing cost when performance is critical.
- •A “good enough” hash for hash tables should minimize collisions and remain effective when certain bits are dropped during bucket indexing.