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https://issues.apache.org/jira/browse/AVRO-160?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12790395#action_12790395
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Philip Zeyliger commented on AVRO-160:
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I like the simpler model. I'm pretty confident that other formats will evolve
(Hadoop sure has a handful: SeqFile, MapFile, TFile, RCFile), and it's good to
start way simple.
To be clear, you're preserving appendability and splittabability, but ditching
schema-evolution-for-appendability. That seems very sensible.
How big are blocks (rule of thumb?)? DataSeries does parallel decompression,
which is easily doable for this file format too, as long as blocks aren't too
big.
You could conceivably store compression codec per block. Probably not worth it.
Should Avro allow a user-specified trailer block? It's simpler if it doesn't.
-- Philip
> file format should be friendly to streaming
> -------------------------------------------
>
> Key: AVRO-160
> URL: https://issues.apache.org/jira/browse/AVRO-160
> Project: Avro
> Issue Type: Improvement
> Components: spec
> Reporter: Doug Cutting
> Assignee: Doug Cutting
>
> It should be possible to stream through an Avro data file without seeking to
> the end.
> Currently the interpretation is that schemas written to the file apply to all
> entries before them. If this were changed so that they instead apply to all
> entries that follow, and the initial schema is written at the start of the
> file, then streaming could be supported.
> Note that the only change permitted to a schema as a file is written is to,
> if it is a union, to add new branches at the end of that union. If it is not
> a union, no changes may be made. So it is still the case that the final
> schema in a file can read every entry in the file and thus may be used to
> randomly access the file.
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