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https://issues.apache.org/jira/browse/HDFS-12534?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16177425#comment-16177425
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Marcelo Vanzin commented on HDFS-12534:
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bq. Are you sure we can split within a single S3 file?
Location != split. You can have x splits all with the same location. I'm pretty
sure reading from a single s3 file using FileInputFormat generates multiple
tasks (one per "split"). You may want to look at how it does that, it might be
all client-side based on some client-side configuration.
> Provide logical BlockLocations for EC files for better split calculation
> ------------------------------------------------------------------------
>
> Key: HDFS-12534
> URL: https://issues.apache.org/jira/browse/HDFS-12534
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: erasure-coding
> Affects Versions: 3.0.0-beta1
> Reporter: Andrew Wang
> Labels: hdfs-ec-3.0-must-do
>
> I talked to [~vanzin] and [~alex.behm] some more about split calculation with
> EC. It turns out HDFS-12222 was resolved prematurely. Applications depend on
> HDFS BlockLocation to understand where the split points are. The current
> scheme of returning one BlockLocation per block group loses this information.
> We should change this to provide logical blocks. Divide the file length by
> the block size and provide suitable BlockLocations to match, with virtual
> offsets and lengths too.
> I'm not marking this as incompatible, since changing it this way would in
> fact make it more compatible from the perspective of applications that are
> scheduling against replicated files. Thus, it'd be good for beta1 if
> possible, but okay for later too.
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