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From "Josh Wills (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CRUNCH-480) AvroParquetFileSource doesn't properly configure user-supplied read schema
Date Mon, 10 Nov 2014 23:24:35 GMT

     [ https://issues.apache.org/jira/browse/CRUNCH-480?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Josh Wills updated CRUNCH-480:
------------------------------
    Attachment: CRUNCH-480.patch

It's not clear to me that a new constructor is needed vs. using the existing constructors
as intended, viz., the AvroType indicates the Schema that should be read (and is configured
as such), and the additional projected schema (if given) is used to project a subset of the
columns. [~tomwhite], how does this patch look to you?

> AvroParquetFileSource doesn't properly configure user-supplied read schema
> --------------------------------------------------------------------------
>
>                 Key: CRUNCH-480
>                 URL: https://issues.apache.org/jira/browse/CRUNCH-480
>             Project: Crunch
>          Issue Type: Bug
>          Components: IO
>    Affects Versions: 0.10.0
>            Reporter: E. Sammer
>            Assignee: Gabriel Reid
>            Priority: Blocker
>         Attachments: CRUNCH-480.patch
>
>
> It seems like AvroParquetFileSource doesn't properly set the configuration param required
to use a user-supplied read schema that differs from the schema in the file.
> Deep in the guts of Parquet (InternalParquetReader#initialize()), I found this:
> {code}
>    this.recordConverter = readSupport.prepareForRead(
>         configuration, extraMetadata, fileSchema,
>         new ReadSupport.ReadContext(requestedSchema, readSupportMetadata));
> {code}
> Later, in Parquet's AvroReadSupport#prepareForRead(), it appears to ignore the supplied
requestedSchema and, instead, looks for the key avro.read.schema in the readSupportMetadata
map. This is seriously kookie code in Parquet (i.e. wrong), but because Crunch doesn't supply
readSupportMetadata, we can never properly supply a read schema. Boooo hisssss.



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