Thanks for raising this up. I spent way way more time on OPIC (almost a year) than robin hood hash map (2 weeks to complete the POC). Glad to see people noticin

Thanks for raising this up. I spent way way more time on OPIC (almost a year) than robin hood hash map (2 weeks to complete the POC). Glad to see people noticing this project :) The other comment pointed out MDBM, which I didn't know about. From their performance number I think this may show that why OPIC robin hood is quite optimal. https://yahooeng.tumblr.com/post/104861108931/mdbm-high-speed-database https://yahooeng.tumblr.com/post/104861108931/mdbm-high-spee... MDMB gives users raw access to the mmaped data and pointers. And from its benchmarks it results 10x faster than rocksdb and leveldb. The design of OPIC has even less overhead (may not be a good thing) than MDBM, and it also works on a mmaped file (or anonymous swap). There's no lock, transaction, or WAL in OPIC. OPIC just brings you the raw performance a hash table can gives you.