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https://issues.apache.org/jira/browse/HDFS-12506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16174901#comment-16174901
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Weiwei Yang commented on HDFS-12506:
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Thanks [~linyiqun], [~nanda] and [~msingh] for all the comments, I have just
uploaded v2 patch to address the feedback. See details below
bq. Should be list all the format of Metadata key for volume, bucket and key in
here ? This will help in readability of the code.
Do you mean to add more doc to explain KSM DB schema? If that is the case, I
have added some doc in {{OzoneConsts}}, hope that is helpful.
bq. should isBucketEmpty be similar to isVolumeEmpty ?
Yes, they can be similar. I have modified the patch a bit to do so.
bq. Created HDFS-12525 to verify volume/bucket name in OzoneClient.
Thanks for adding a task to track this.
Let me know if I miss anything. Thanks all.
> Ozone: ListBucket is too slow
> -----------------------------
>
> Key: HDFS-12506
> URL: https://issues.apache.org/jira/browse/HDFS-12506
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ozone
> Reporter: Weiwei Yang
> Assignee: Weiwei Yang
> Priority: Blocker
> Labels: ozoneMerge, performance
> Attachments: HDFS-12506-HDFS-7240.001.patch,
> HDFS-12506-HDFS-7240.002.patch
>
>
> Generated 3 million keys in ozone, and run {{listBucket}} command to get a
> list of buckets under a volume,
> {code}
> bin/hdfs oz -listBucket http://15oz1.fyre.ibm.com:9864/vol-0-15143 -user wwei
> {code}
> this call spent over *15 seconds* to finish. The problem was caused by the
> inflexible structure of KSM DB. Right now {{ksm.db}} stores keys like
> following
> {code}
> /v1/b1
> /v1/b1/k1
> /v1/b1/k2
> /v1/b1/k3
> /v1/b2
> /v1/b2/k1
> /v1/b2/k2
> /v1/b2/k3
> /v1/b3
> /v1/b4
> {code}
> keys are sorted in nature order so when we do list buckets under a volume e.g
> /v1, we need to seek to /v1 point and start to iterate and filter keys, this
> ends up with scanning all keys under volume /v1. The problem with this design
> is we don't have an efficient approach to locate all buckets without scanning
> the keys.
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