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https://issues.apache.org/jira/browse/HADOOP-14965?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-14965:
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Attachment: HADOOP-14965-004.patch
patch 004; against trunk, resubmit.
Test: s3 ireland.
I have been using this, it very good as it avoids you having to decide when you
create an FS instance whether you want columnar IO or sequential. Which allows
you to mix columnar/snappy data with gzipped data in the same store.
> s3a input stream "normal" fadvise mode to be adaptive
> -----------------------------------------------------
>
> Key: HADOOP-14965
> URL: https://issues.apache.org/jira/browse/HADOOP-14965
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.8.1
> Reporter: Steve Loughran
> Assignee: Steve Loughran
> Attachments: HADOOP-14965-001.patch, HADOOP-14965-002.patch,
> HADOOP-14965-003.patch, HADOOP-14965-004.patch
>
>
> HADOOP-14535 added seek optimisation to wasb, but rather than require the
> caller to declare sequential vs random, it works out for itself.
> # defaults to sequential, lazy seek
> # if the caller ever seeks backwards, switches to random IO.
> This means that on the use pattern of columnar stores: of go to end of file,
> read summary, then go to columns and work forwards, will switch to random IO
> after that first seek back (cost: one aborted HTTP connection)/.
> Where this should benefit the most is in downstream apps where you are
> working with different data sources in the same object store/running of the
> same app config, but have different read patterns. I'm seeing exactly this in
> some of my spark tests, where it's near impossible to set things up so that
> .gz files are read sequentially, but ORC data is read in random IO
> I propose the "normal" fadvise => adaptive, sequential==sequential always,
> random => random from the outset.
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