1BRC: One Billion Row Challenge in Lua

Lua implementation of Gunnar's 1 billion row challenge:

• https://www.morling.dev/blog/one-billion-row-challenge
• https://github.com/gunnarmorling/1brc

Rules

No dependencies allowed, only lua standard library, and no C (this include the ffi lib of luajit). The programm should work in a standalone file. Lua or LuaJIT are allowed.

Input

The input file is a list of temperature measurments in some cities. The form il of:

City;temperature
City;temperature
(...)
City;temperature

• It is UTF-8 encoded.
• city names could have spaces or hyphens in it, but it is garenteed that they do not contain semicolons ;.
• Temperatures range frome -99.0 to 99.0, and always contains one decimal digit. So you could have : 1.3, -7.4, 48.4, -61.1.

The script to generate the data only contains ~400 cities, but the solution shold not depend on theese. It should work no matter the set and the number of cities.

Output

The output should be of the form

{City1=min/mean/max, City2=min/mean/max, (...), Cityn=min/mean/max}

With the cities arranged in an alphabetical order.

Creating the measurements file with 1B rows

Just run the scrit "createMeasurements.lua" with lua or luajit (it is much faster with luajit):

luajit ./createMeasurements.lua

or

lua ./createMeasurements.lua

Be patient as it can take more than a minute to have the file generated.

Optionnally, you can pass extra arguments to the script :

• The first one for the number of rows (default = 1 000 000 000)
• The second one for the output file (default = ./measurements.txt)

Results

The baseline is baseline.lua, and your output should match this one.

On my laptop (Ryzen 5 7640 12 cores, 32GB RAM) :

#	Result (m:s.ms)	Implementation	Interpreter	Submitter
1.	00:10:915	1brc_BenjaminV.lua	luajit 2.1	benjamin-voisin
2.	00:11:282	1brc_felipeguilhermefs.lua	luajit 2.1	felipeguilhermefs
3.	00:44:864	1brc_MikuAuahDark.lua	luajit 2.1	MikuAuahDark
3.	01:30:693	1brc_BenjaminV.lua	lua 5.4	benjamin-voisin
4.	05:51:029	baseline.lua	luajit 2.1	baseline
5.	08:57:189	baseline.lua	lua 5.4	baseline

For comparaison with other languages, on the same machine, the fastest Python Implementation I found runs for 25 seconds link, and from the original Java repository, the fastest Java implementation is ~3 seconds with the JVM and ~1 second when compiled to a native executable. So I'm very happy with the 10 seconds performance!

Submissions

For any submissions please open a PR !