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From "Weiwei Yang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-12506) Ozone: ListBucket is too slow
Date Wed, 20 Sep 2017 07:40:01 GMT
Weiwei Yang created HDFS-12506:
----------------------------------

             Summary: 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


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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