Bitcoin full node and query server
Nov 5, 2024
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josie18:43
somewhat unrelated, im very curious what insights you guys have regarding mmap'd db architectures. ive been exploring mdbx as a replacement for leveldb in core as sort of a moonshot side experiment, and mdbx (fork of lmdb) is essentially a mmap'd shadow paged btree. we saw some really promising benchmarks, but also a ton of write amplification. curious if you guys have any insights, since it seems you've rolled your own mmaped db architecture?
jungly19:26
The database community is very split on mmap. Andy Pavlo is fighting a big battle to get DBMSes to not use mmap for a generic database. https://db.cs.cmu.edu/mmap-cidr2022/ The story about mangodb is illuminating.
On the other hand, Eric has shown if you know the precise queries and you know the schema intimately, you can make it work. I would stay away from a generic mmap database, or at least let's discuss the issues listed in the paper below.