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https://issues.apache.org/jira/browse/HADOOP-12444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14936637#comment-14936637
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Thomas Demoor commented on HADOOP-12444:
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I recall a discussion about this functionality in the comments of another
ticket somewhere but I guess we forgot to create a ticket for it. Thanks for
posting the issue and especially the patch!
P.S. I moved this from HDFS to Hadoop Common under the s3a phase 2
stabilisation task, nothing to worry about ;)
> Consider implementing lazy seek in S3AInputStream
> -------------------------------------------------
>
> Key: HADOOP-12444
> URL: https://issues.apache.org/jira/browse/HADOOP-12444
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.7.1
> Reporter: Rajesh Balamohan
> Attachments: HADOOP-12444.WIP.patch
>
>
> - Currently, "read(long position, byte[] buffer, int offset, int length)" is
> not implemented in S3AInputStream (unlike DFSInputStream). So,
> "readFully(long position, byte[] buffer, int offset, int length)" in
> S3AInputStream goes through the default implementation of seek(), read(),
> seek() in FSInputStream.
> - However, seek() in S3AInputStream involves re-opening of connection to S3
> everytime
> (https://github.com/apache/hadoop/blob/trunk/hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/S3AInputStream.java#L115).
>
> - It would be good to consider having a lazy seek implementation to reduce
> connection overheads to S3. (e.g Presto implements lazy seek.
> https://github.com/facebook/presto/blob/master/presto-hive/src/main/java/com/facebook/presto/hive/PrestoS3FileSystem.java#L623)
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