Similar to how the upcoming WAL2 works in SQLite, could do it atomically or "concurrent safe" like: - Main count file. - 2 "Append" files. ====== - Append '

Similar to how the upcoming WAL2 works in SQLite, could do it atomically or "concurrent safe" like: - Main count file. - 2 "Append" files. ====== - Append 'a' to append file 1. - After some time, swap append file 1 with 2. - Count up 'a' in non-active append file 1, add it to main count. Then just repeat, swapping append files.