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Posted to issues@beam.apache.org by "Beam JIRA Bot (Jira)" <ji...@apache.org> on 2020/09/09 17:08:02 UTC

[jira] [Assigned] (BEAM-10111) Create methods in fileio to read from / write to archive files

     [ https://issues.apache.org/jira/browse/BEAM-10111?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Beam JIRA Bot reassigned BEAM-10111:
------------------------------------

    Assignee:     (was: Ashwin Ramaswami)

> Create methods in fileio to read from / write to archive files
> --------------------------------------------------------------
>
>                 Key: BEAM-10111
>                 URL: https://issues.apache.org/jira/browse/BEAM-10111
>             Project: Beam
>          Issue Type: Improvement
>          Components: io-py-files
>            Reporter: Ashwin Ramaswami
>            Priority: P2
>              Labels: stale-assigned
>          Time Spent: 40m
>  Remaining Estimate: 0h
>
> Discussion here: https://lists.apache.org/thread.html/r784701bda9edf9a52d5ee593f44a8870aab96b6df1dc8eedd2c8a249%40%3Cdev.beam.apache.org%3E
> It would be good to be able to read from / write to archive files (.zip, .tar) using fileio. The difference between this proposal and what we already have with CompressionTypes is that this would allow converting one file -> multiple files and vice versa. Here's how it might look like:
> *Reading all contents from archive files:*
> {code:python}
>     files = (
>         p
>         | fileio.MatchFiles('hdfs://path/to/*.zip')
>         | fileio.ExtractMatches()
>         | fileio.MatchAll()
>         | fileio.ReadMatches()
>         | beam.Map(lambda x: (x.metadata.path, x.metadata._parent_archive_paths, x.read_utf8()))
>     )
> {code}
> *Nested archive example:* (look for all inside of .tar inside of .zip)
> {code:python}
>     files = (
>         p
>         | fileio.MatchFiles('hdfs://path/to/*.zip')
>         | fileio.ExtractMatches()
>         | fileio.MatchAll('*.tar')
>         | fileio.Extract()
>         | fileio.MatchAll() # gets all entries
>         | fileio.ReadMatches()
>         | beam.Map(lambda x: (x.metadata.path, x.read_utf8()))
>     )
> {code}
> Note that in this case, this would involve modifying MatchAll() to take an argument, which would filter the files in the pcollection in the earlier stage of the pipeline.
> *Reading from archive files and explicitly specifying the archive type (when it can't be inferred by the file extension):*
> {code:python}
>     files = (
>         p
>         | fileio.MatchFiles('hdfs://path/to/archive')
>         | fileio.ExtractMatches(archivesystem=ArchiveSystem.TAR)
>         | fileio.MatchAll(archive_path='*.txt')
>         | fileio.ReadMatches()
>         | beam.Map(lambda x: (x.metadata.path, x.read_utf8()))
>     )
> {code}
> `ArchiveSystem` would be a generic class, just like `FileSystem`, which would allow for different implementations of methods such as `list()` and `extract()`. It would be implemented for .zip, .tar, etc.
> *Writing multiple files to an archive file:*
> {code:python}
>     files = (
>         p
>         | fileio.MatchFiles('hdfs://path/to/files/*.txt')
>         | fileio.CompressMatches(archivesystem=ArchiveSystem.ZIP)
>         | fileio.WriteToArchive("output.zip")
>     )
> {code}
> *Writing to a .tar.gz file:*
> {code:python}
>     files = (
>         p
>         | fileio.MatchFiles('hdfs://path/to/files/*.txt')
>         | fileio.CompressMatches(archivesystem=ArchiveSystem.TAR)
>         | fileio.WriteToArchive("output.tar.gz")
>     )
> {code}



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