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https://issues.apache.org/jira/browse/HDFS-12506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16173440#comment-16173440
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Xiaoyu Yao edited comment on HDFS-12506 at 9/20/17 4:28 PM:
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We should keep a common prefix for all higher level containers like (volume,
bucket) to avoid mixing the prefix with objects.
If we don't have /#v1/#b1, list volume might still have the same overhead of
iterating all the keys like we had for bucket case here unless you want use
/v1/# prefix to listvolume. Both should work.
was (Author: xyao):
We should keep a common prefix for all higher level containers like (volume,
bucket) to avoid mixing the prefix with objects.
If we don't have /#v1/#b1, list volume will still have the same overhead of
iterating all the keys like we had for bucket case here.
> 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
> Priority: Blocker
> Labels: ozoneMerge
>
> 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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