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https://issues.apache.org/jira/browse/CRUNCH-480?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14206494#comment-14206494
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Tom White commented on CRUNCH-480:
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Josh - I agree that new constructors aren’t needed on AvroParquetFileSource
since the read schema comes from the AvroType. I hadn't seen the includeField
method on the builder as a way of specifying the projection - that seems
reasonable to me. It's not clear why getBundle() sets a projection schema, even
when no fields are included.
Gabriel - what's the bug in default handling in Parquet? We should fix it.
BTW {{.set(RuntimeParameters.DISABLE_COMBINE_FILE, "true")}} can be removed
from Parquet 1.4 since it uses FileSplit now.
> 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-480.1.patch, 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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