The goal of the challenge is to write a program for retrieving temperature measurement values from a text file and calculating the min, mean, and max temperature per weather station. And the file has 1,000,000,000 rows.

The text file has a simple structure with one measurement value per row:

Hamburg;12.0
Bulawayo;8.9
Palembang;38.8
St. John's;15.2
Cracow;12.6

The program should print out the min, mean, and max values per station, alphabetically ordered like so:

{Abha=5.0/18.0/27.4, Abidjan=15.7/26.0/34.1, Abéché=12.1/29.4/35.6, Accra=14.7/26.4/33.1, Addis Ababa=2.1/16.0/24.3, Adelaide=4.1/17.3/29.7, ...}

The goal of the challenge is to create the fastest implementation for this task.

onebrcgo is a solution to the one billion row challenge with Go.

Run:

go test -cpuprofile cpu.prof -memprofile mem.prof -bench .

And then:

go tool pprof cpu.prof

Or:

go tool pprof mem.prof

onebrcgo is released under the MIT license.