[GitHub] [arrow] boshek commented on a diff in pull request #13183: ARROW-16144: [R] Write compressed data streams (particularly over S3)

[GitBox <gi...@apache.org>]

boshek commented on code in PR #13183:
URL: https://github.com/apache/arrow/pull/13183#discussion_r876183135


##########
r/R/io.R:
##########
@@ -292,7 +292,7 @@ make_readable_file <- function(file, mmap = TRUE, compression = NULL, filesystem
   file
 }
 
-make_output_stream <- function(x, filesystem = NULL) {
+make_output_stream <- function(x, filesystem = NULL, compression = NULL) {

Review Comment:
   So for the `parquet.snappy` or even `snappy.parquet` I think it works because "snappy" isn't included here: 
   https://github.com/apache/arrow/blob/3df2e0568240d6b629c0a3163df21a1a2a160810/r/R/io.R#L325-L330
   
   But if someone tried something like this we do get an error that isn't super informative. I _think_ this is outside this PR so could the resolution here be to open another ticket for this specifically? 
   ``` r
   library(arrow, warn.conflicts = FALSE)
   tf <- tempfile(fileext = ".parquet.gz")
   write_parquet(data.frame(x = 1:5), tf, compression = "gzip", compression_level = 5)
   read_parquet(tf)
   #> Error: file must be a "RandomAccessFile"
   ```



##########
r/tests/testthat/test-s3-minio.R:
##########
@@ -54,6 +54,24 @@ if (arrow_with_s3() && process_is_running("minio server")) {
     )
   })
 
+  test_that("read/write compressed csv by filesystem", {
+    dat <- tibble(x = seq(1, 10, by = 0.2))

Review Comment:
   I will add in to be defensive. 



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