R read / write

library(data.table)
library(feather)
library(microbenchmark)

testDT <- rbindlist(replicate(2e5L, iris, simplify = FALSE))
format(object.size(testDT), "Mb") # 1030 Mb ~ 1 Gb

fwrite(testDT, "test.csv")
write_feather(testDT, "test.feather")
saveRDS(testDT, "test.rds")
saveRDS(testDT, "test2.rds", compress = FALSE)

file.size("test.csv")     #  761600059 ~  726 Mb
file.size("test.feather") # 1080000640 ~ 1030 Mb
file.size("test.rds")     #    8296749 ~ 7.91 Mb
file.size("test2.rds")    # 1080000557 ~ 1030 Mb

microbenchmark(saveRDS = local(saveRDS(testDT, "test.rds")),
               saveRDS_no_compress = local(saveRDS(testDT, "test2.rds", compress = FALSE)),
               write_feather = local(write_feather(testDT, "test.feather")),
               fwrite = local(fwrite(testDT, "test.csv")),
               readRDS = local({testDT <- readRDS("test.rds")}),
               readRDS_no_compress = local({testDT2 <- readRDS("test2.rds")}),
               read_feather = local(as.data.frame(read_feather("test.feather"))),
               fread = local(fread("test.csv")),
               times = 20L)
# Unit: milliseconds
#                 expr        min         lq       mean     median         uq       max neval
#              saveRDS  7516.5394  7602.5767  7770.3196  7686.7767  7935.6723  8158.606    20
#  saveRDS_no_compress  1417.6231  1446.3086  1756.1208  1514.9383  1729.1255  5045.703    20
#        write_feather  4571.6872  5459.9026  6384.5605  6115.1136  7116.2653  9478.708    20
#               fwrite  2271.8399  2382.4617  2525.4811  2474.2916  2527.3236  3416.503    20
#  readRDS_no_compress  1274.8282  1395.2916  1516.4908  1513.2334  1658.3701  1816.422    20
#              readRDS  2118.5699  2252.7583  2390.4575  2385.7802  2518.7170  2830.373    20
#         read_feather   565.3394   612.3607   727.3408   621.3474   900.5532  1136.687    20
#                fread 57886.2133 58140.8123 59768.2511 58742.0473 60783.4750 65087.893    20

# devtools::install_github("bwlewis/lz4")
library(lz4)

testDT <- rbindlist(replicate(2e5L, iris, simplify = FALSE))
writeBin(lzCompress(serialize(testDT, NULL)), "test.lz4")
testDT2 <- unserialize(lzDecompress(readBin("test.lz4", "raw", file.info("test.lz4")$size)))
all.equal(testDT, testDT2) # TRUE

microbenchmark(lz4write = local(writeBin(lzCompress(serialize(testDT, NULL)), "test.lz4")),
               lz4read = local(unserialize(lzDecompress(readBin("test.lz4", "raw", file.info("test.lz4")$size)))),
               times = 20L)
# Unit: seconds
#     expr      min       lq     mean   median       uq      max neval
# lz4write 3.425010 3.646188 3.753905 3.733799 3.841660 4.198919    20
#  lz4read 1.493515 1.566712 1.646142 1.603984 1.746855 1.797484    20