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https://issues.apache.org/jira/browse/AVRO-1418?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13854215#comment-13854215
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Doug Cutting commented on AVRO-1418:
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First, the best practice is not to propose solutions in the Jira description,
but rather to just describe the problem there. The solution should be
developed in the comments. This style minimizes edits, which are hard to
follow by email.
Second, can't we simply add the new sync() method to the existing classes
rather than adding a number of new subclasses? The new subclasses may
abstractly seem more elegant but I worry that they overly complicate the API.
The ability to sync() seems like something that the base implementation would
benefit from too, no?
> AvroMultipleOutputs should support sync-able writers
> ----------------------------------------------------
>
> Key: AVRO-1418
> URL: https://issues.apache.org/jira/browse/AVRO-1418
> Project: Avro
> Issue Type: New Feature
> Reporter: Deepak Kumar V
>
> DataFileWriter supports APIs like sync() (that allows to emit synchronization
> markers) so that DataFileReader could later use sync() or seek() to move to a
> particular synchronization point.
> AvroMultipleOutputs does not support or provide a way to invoke sync on its
> individual writers. One could extend its behavior, however its design is
> closed for extension. (All states are private and getRecordWriter() are
> private). Hence AvroMultipleOutputs must first be modified so as to support
> extension and additional classes must be provided to support a synch able
> MutilpleOutputFormats.
> Solution
> ======
> I) MarkableAvroMultipleOutputs : Allows users to set synchronization points
> before/after writing Key-Value pairs with AvroMultipleOutputs.write()
> A public api to invoke sync on a named output.
> Ex: public void sync(String namedOutput, String baseOutputPath) throws
> IOException, InterruptedException {}
> To achieve above AvroMultipleOutputs should be modified so as to allow
> support for additional behavior. The following must be marked as protected
> instead of private
> 1) private static void checkBaseOutputPath(String outputPath) {} from
> private.
> 2) private static void checkNamedOutputName(JobContext job, String
> namedOutput, boolean alreadyDefined) {} from private.
> 3) private TaskInputOutputContext<?, ?, ?, ?> context;
> 4) private Set<String> namedOutputs;
> 5) private synchronized RecordWriter getRecordWriter(TaskAttemptContext
> taskContext, String baseFileName)
> II) AvroKeyValueRecordWriter that is used by AvroMultipleOutputs as writers
> for individual writers is again closed for extension. It must allow to invoke
> sync() on writer.
> To achieve that the following private members must be marked protected.
> 1) private final DataFileWriter<GenericRecord> mAvroFileWriter;
> A MarkableAvroKeyValueRecordWriter must be provided that exposes a public API
> to invoke sync on its writer.
> public void sync() throws IOException {}
> III) A MarkableAvroKeyValueOutputFormat that extends AvroKeyValueOutputFormat
> and uses MarkableAvroKeyValueRecordWriter.
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