Jeffrey Wong created ARROW-4027:
-----------------------------------
Summary: Reading partitioned datasets using RecordBatchFileReader
into R
Key: ARROW-4027
URL: https://issues.apache.org/jira/browse/ARROW-4027
Project: Apache Arrow
Issue Type: Bug
Components: R
Affects Versions: 0.11.1
Environment: Ubuntu 16.04, building R package from master on github
Reporter: Jeffrey Wong
I have a parquet dataset (which originally came from Hive) stored locally in
the directory `data/`. It has 4 files in it
```
data/foo1
data/foo2
data/foo3
data/foo4
```
Using pyarrow I can read them via
`pq.read_table("data/foo1").to_pandas()`
I am trying to read them into R using `read_table("data/foo1")`, but I receive
this error.
```
Error in ipc___RecordBatchFileReader__Open(file) :
Invalid: Not an Arrow file
```
>From debugging, I've traced it to this line
>https://github.com/apache/arrow/blob/d54a154263e1dba5515ebe1a8423a676a01e3951/r/R/RecordBatchReader.R#L112,
> which then goes to this Rcpp code
>https://github.com/apache/arrow/blob/d54a154263e1dba5515ebe1a8423a676a01e3951/r/src/recordbatchreader.cpp#L85.
> It seems that this c++ function is expecting a single "[file like
>object](https://arrow.apache.org/docs/cpp/classarrow_1_1ipc_1_1_record_batch_file_reader.html#a7e6c66ca32d75bc8d4ee905982d9819e)";
> I think because my data is split, there is a footer that is supposed to
>contain a file layout and schema which cannot be found, hence the error Not an
>Arrow file.
If I pass the whole directory using `read_table("data/")` I will get
```
Error in ipc___RecordBatchFileReader__Open(file) :
IOError: Error reading bytes from file: Is a directory
```
I cannot post the original dataset online, and I don't know what aspect of my
data causes the code to break, so I don't quite know how to post a reproducible
example. Tips on how to generate a partitioned dataset would be great
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