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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 4:31 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.
Otherwise, list volume might still have the same overhead of iterating all the
keys like we had for bucket case here unless you choose the right prefix like
{{/v1/#}} to listVolume. Both proposal 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 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.
> 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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