# data gen
Rscript -e 'library(data.table); set.seed(108); N = 1e8; fwrite(data.table(id = sample(N), v1=1L), "d1.csv"); fwrite(data.table(id = sample(N), v2=2L), "d2.csv")'
# join
R -q
library(data.table)
d1 = fread("d1.csv")
d2 = fread("d2.csv")
system.time(d1[d2, on="id"])
# user system elapsed
# 51.929 9.861 24.909
q("no")
R -q
library(data.table)
d1 = fread("d1.csv")
d2 = fread("d2.csv", key="id")
system.time(d1[d2, on="id"])
# user system elapsed
# 29.645 6.587 13.537
q("no")
R -q
library(data.table)
d1 = fread("d1.csv")
d2 = fread("d2.csv", index="id")
system.time(d1[d2, on="id"])
# user system elapsed
# 51.679 9.918 23.874
q("no")
