## What changes were proposed in this pull request?
This PR targets to support Arrow optimization for conversion from R DataFrame to Spark DataFrame.
Like PySpark side, it falls back to non-optimization code path when it's unable to use Arrow optimization.
This can be tested as below:
```bash
$ ./bin/sparkR --conf spark.sql.execution.arrow.enabled=true
```
```r
collect(createDataFrame(mtcars))
```
### Requirements
- R 3.5.x
- Arrow package 0.12+
```bash
Rscript -e 'remotes::install_github("apache/arrowapache-arrow-0.12.0", subdir = "r")'
```
**Note:** currently, Arrow R package is not in CRAN. Please take a look at ARROW-3204.
**Note:** currently, Arrow R package seems not supporting Windows. Please take a look at ARROW-3204.
### Benchmarks
**Shall**
```bash
sync && sudo purge
./bin/sparkR --conf spark.sql.execution.arrow.enabled=false
```
```bash
sync && sudo purge
./bin/sparkR --conf spark.sql.execution.arrow.enabled=true
```
**R code**
```r
createDataFrame(mtcars) # Initializes
rdf <- read.csv("500000.csv")
test <- function() {
options(digits.secs = 6) # milliseconds
start.time <- Sys.time()
createDataFrame(rdf)
end.time <- Sys.time()
time.taken <- end.time - start.time
print(time.taken)
}
test()
```
**Data (350 MB):**
```r
object.size(read.csv("500000.csv"))
350379504 bytes
```
"500000 Records" http://eforexcel.com/wp/downloads-16-sample-csv-files-data-sets-for-testing/
**Results**
```
Time difference of 29.9468 secs
```
```
Time difference of 3.222129 secs
```
The performance improvement was around **950%**.
Actually, this PR improves around **1200%**+ because this PR includes a small optimization about regular R DataFrame -> Spark DatFrame. See https://github.com/apache/spark/pull/22954#discussion_r231847272
### Limitations:
For now, Arrow optimization with R does not support when the data is `raw`, and when user explicitly gives float type in the schema. They produce corrupt values.
In this case, we decide to fall back to non-optimization code path.
## How was this patch tested?
Small test was added.
I manually forced to set this optimization `true` for _all_ R tests and they were _all_ passed (with few of fallback warnings).
**TODOs:**
- [x] Draft codes
- [x] make the tests passed
- [x] make the CRAN check pass
- [x] Performance measurement
- [x] Supportability investigation (for instance types)
- [x] Wait for Arrow 0.12.0 release
- [x] Fix and match it to Arrow 0.12.0
Closes#22954 from HyukjinKwon/r-arrow-createdataframe.
Lead-authored-by: hyukjinkwon <gurwls223@apache.org>
Co-authored-by: Hyukjin Kwon <gurwls223@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
e8982ca7ad