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https://issues.apache.org/jira/browse/ARROW-4027?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wes McKinney closed ARROW-4027.
-------------------------------
Resolution: Duplicate
[~jeffreyw] reading Parquet files is not yet supported in R, see ARROW-3731 for
a discussion of adding an R API. Help would be appreciated
> 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
> Priority: Major
>
> 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
> ```
> So, how can I use the R package to correctly read multiple parquet files? If
> I need to call RecordBatchFileReader with a pointer to the footer, file
> layout and schema, how do I find the footer of the dataset?
>
>
> 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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