Hacker News Reader

Since you mentioned MMAP: "Are You Sure You Want to Use MMAP in Your Database Management System?" https://www.cidrdb.org/cidr2022/papers/p13-crotty.pdf

View on HN

It's also worth while reading the rebuttal from ravendb: https://ayende.com/blog/196161-C/re-are-you-sure-you-want-to...

Also worth mentioning LMDB, probably the fastest embedded K/V db in terms of read perf uses mmap.

Dataset was 20x times larger than available RAM in that case, so it makes sense that OS cashing was useless and only induced overhead..

Another potential issue was that they compared their mmap code to fio O_DIRECT code, which kinda not clean experiment, fio could be just much more optimized itself..

Besides this point, I mostly mentioned it as an example of probably the simplest in-memory yet disk-backed database imaginable. For example, if you want to implement any sort of transactions, you don't want to actually do anything like fsync until you start trying to commit the data.

Reply on news.ycombinator.com