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https://issues.apache.org/jira/browse/HADOOP-13282?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran updated HADOOP-13282:
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Description:
If the etags of blobs were exported via {{getFileChecksum()}}, it'd be possible
to probe for a blob being in sync with a local file. Distcp could use this to
decide whether to skip a file or not.
Now, there's a problem there: distcp needs source and dest filesystems to
implement the same algorithm. It'd only work out the box if you were copying
between S3 instances. There are also quirks with encryption and multipart: [s3
docs|http://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html].
At the very least, it's something which could be used when indexing the FS, to
check for changes later.
was:
If the etags of blobs were exported via {{getFileChecksum() }}, it'd be
possible to probe for a blob being in sync with a local file. Distcp could use
this to decide whether to skip a file or not.
Now, there's a problem there: distcp needs source and dest filesystems to
implement the same algorithm. It'd only work out the box if you were copying
between S3 instances. There are also quirks with encryption and multipart: [s3
docs|http://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html].
At the very least, it's something which could be used when indexing the FS, to
check for changes later.
> S3 blob etags to be made visible in status/getFileChecksum() calls
> ------------------------------------------------------------------
>
> Key: HADOOP-13282
> URL: https://issues.apache.org/jira/browse/HADOOP-13282
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 2.9.0
> Reporter: Steve Loughran
> Priority: Minor
>
> If the etags of blobs were exported via {{getFileChecksum()}}, it'd be
> possible to probe for a blob being in sync with a local file. Distcp could
> use this to decide whether to skip a file or not.
> Now, there's a problem there: distcp needs source and dest filesystems to
> implement the same algorithm. It'd only work out the box if you were copying
> between S3 instances. There are also quirks with encryption and multipart:
> [s3
> docs|http://docs.aws.amazon.com/AmazonS3/latest/API/RESTCommonResponseHeaders.html].
> At the very least, it's something which could be used when indexing the FS,
> to check for changes later.
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