HyukjinKwon commented on a change in pull request #22954: [WIP][SPARK-25981][R]
Enables Arrow optimization from R DataFrame to Spark DataFrame
URL: https://github.com/apache/spark/pull/22954#discussion_r250585248
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File path: R/pkg/R/SQLContext.R
##########
@@ -147,6 +147,89 @@ getDefaultSqlSource <- function() {
l[["spark.sql.sources.default"]]
}
+writeToFileInArrow <- function(fileName, rdf, numPartitions) {
+ requireNamespace1 <- requireNamespace
+
+ # For some reasons, Arrow R API requires to load 'defer_parent' which is
from 'withr' package.
+ # This is a workaround to avoid this error. Otherwise, we should directly
load 'withr'
+ # package, which CRAN complains about.
+ defer_parent <- function(x, ...) {
+ if (requireNamespace1("withr", quietly = TRUE)) {
+ defer_parent <- get("defer_parent", envir = asNamespace("withr"),
inherits = FALSE)
+ defer_parent(x, ...)
+ } else {
+ stop("'withr' package should be installed.")
+ }
+ }
+
+ # R API in Arrow is not yet released. CRAN requires to add the package in
requireNamespace
+ # at DESCRIPTION. Later, CRAN checks if the package is available or not.
Therefore, it works
+ # around by avoiding direct requireNamespace.
+ if (requireNamespace1("arrow", quietly = TRUE)) {
+ record_batch <- get("record_batch", envir = asNamespace("arrow"), inherits
= FALSE)
+ record_batch_stream_writer <- get(
+ "record_batch_stream_writer", envir = asNamespace("arrow"), inherits =
FALSE)
Review comment:
FWIW, sparklyr and arrow implementation uses the same trick to avoid CRAN
failure.
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