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https://issues.apache.org/jira/browse/HADOOP-14266?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15969811#comment-15969811
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Mingliang Liu commented on HADOOP-14266:
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[~fabbri] your comments are very precise. Thanks for the clear explanation! I
suggest we update the description of this JIRA using most of the above comments
when the patch is final.
After reading your comment, I also have two basic ideas to optimize further
along with your proposed future enhancement.
# For the {{!recursive && isAuthoritative}} case, we can return metadata store
cachedFilesIterator results without asking S3. This will be similar to
{{listLocatedStatus()}}.
# If we have returned value order guarantee from both S3 list object request
and metadata store {{DescendantsIterator}}, in {{FileStatusListingIterator}} we
can maintain two moving iterators and avoid pre-iterating providedStatus, in
which way it uses much less memory (no providedStatus HashSet then).
I will re-visit these two ideas again next week. Perhaps we can address them
later.
> S3Guard: S3AFileSystem::listFiles() to employ MetadataStore
> -----------------------------------------------------------
>
> Key: HADOOP-14266
> URL: https://issues.apache.org/jira/browse/HADOOP-14266
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: HADOOP-13345
> Reporter: Mingliang Liu
> Assignee: Mingliang Liu
> Attachments: HADOOP-14266-HADOOP-13345.000.patch,
> HADOOP-14266-HADOOP-13345.001.patch, HADOOP-14266-HADOOP-13345.002.patch,
> HADOOP-14266-HADOOP-13345.003.patch, HADOOP-14266-HADOOP-13345.003.patch,
> HADOOP-14266-HADOOP-13345.004.patch, HADOOP-14266-HADOOP-13345-005.patch,
> HADOOP-14266-HADOOP-13345.005.patch, HADOOP-14266-HADOOP-13345.006.patch
>
>
> Similar to [HADOOP-13926], this is to track the effort of employing
> MetadataStore in {{S3AFileSystem::listFiles()}}.
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