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https://issues.apache.org/jira/browse/HADOOP-13449?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mingliang Liu updated HADOOP-13449:
-----------------------------------
    Attachment: HADOOP-13449-HADOOP-13345.001.patch

Thanks for asking [~eddyxu]. I attach the v1 patch for quick feedback.

# I changed the base unit test as the {{owner}}, {{group}} and {{permission}} 
etc are not part of the metadata we're interested in by now.
# We store the {{is_empty}} for directory in the DynamoDB (DDB) metadata store 
now. We have to update this information in a consistent and efficient way. We 
don't want to check the parent directory every time we delete/put a file item. 
At least we can optimize this when deleting a subtree.
# The contract assumes we create the direct parent directory (other ancestors 
should be taken care of by the clients/callers) when putting a new file item. I 
checked the in-memory local metadata store and it implements this idea. This 
may be not efficient to DDB. Basically for putting X items, we have to issue 
2X~3X DDB requests (X for putting file, X for checking its parent directories, 
and possible X for updating its parent directories). I'm wondering if we can 
also let the client/caller pre-create the direct parent directory as other 
ancestors.
This is root cause of the only left 2 of 16 failing unit tests, i.e. 
{{testPutDirListing}} and {{testPutNew}}.
# As to replacing FileStatus with S3AFileStatus in {{PathMetadata}}, I'm +0 for 
the idea. If we do agree on the switch, [HADOOP-13736] is basically good to me. 
If not, I can live with the similar way to {{S3AFileSystem}} vs. {{FileSystem}} 
in the {{MetadataStore#initialize()}}.
# I need to review [HADOOP-13651] and revisit the patch after catching up the 
current discussion. Will post v2 patch in one week. I will also handle the 
{{isAuthoritative}} in the next patch. Storing an extra field is a good and 
simple idea. Any idea how client sets/gets this value?

Thanks,

> S3Guard: Implement DynamoDBMetadataStore.
> -----------------------------------------
>
>                 Key: HADOOP-13449
>                 URL: https://issues.apache.org/jira/browse/HADOOP-13449
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs/s3
>            Reporter: Chris Nauroth
>            Assignee: Mingliang Liu
>         Attachments: HADOOP-13449-HADOOP-13345.000.patch, 
> HADOOP-13449-HADOOP-13345.001.patch
>
>
> Provide an implementation of the metadata store backed by DynamoDB.



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