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https://issues.apache.org/jira/browse/ARROW-18089?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dewey Dunnington updated ARROW-18089:
-------------------------------------
Fix Version/s: 12.0.0
(was: 11.0.0)
> [R] Cannot read_parquet on http URL
> -----------------------------------
>
> Key: ARROW-18089
> URL: https://issues.apache.org/jira/browse/ARROW-18089
> Project: Apache Arrow
> Issue Type: Bug
> Components: R
> Reporter: Neal Richardson
> Priority: Critical
> Labels: triaged
> Fix For: 12.0.0
>
>
> {code}
> u <-
> "https://raw.githubusercontent.com/apache/arrow/master/r/inst/v0.7.1.parquet";
> read_parquet(u)
> # Error: file must be a "RandomAccessFile"
> read_parquet(url(u))
> # Error: file must be a "RandomAccessFile"
> {code}
> The issue is that urls get turned into InputStream by {{make_readable_file}},
> and parquet requires RandomAccessFile.
> {code}
> arrow:::make_readable_file(u)
> # InputStream
> {code}
> There are two relevant codepaths in make_readable_file: if given a string
> URL, it tries {{FileSystem$from_uri()}} and falls back to
> {{MakeRConnectionInputStream}}, which returns InputStream not
> RandomAccessFile. If provided a connection object (i.e. {{url(u)}}), it tries
> MakeRConnectionRandomAccessFile first and falls back to
> MakeRConnectionInputStream. If you provide a {{url()}} it does fall back to
> InputStream:
> {code}
> arrow:::MakeRConnectionRandomAccessFile(url(u))
> # Error: Tell() returned an error
> {code}
> If we truly can't work with a HTTP URL in read_parquet, we should at least
> document that. We could also do the workaround of downloading to a tempfile
> first.
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