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https://issues.apache.org/jira/browse/HDFS-12506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16174418#comment-16174418
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Yiqun Lin commented on HDFS-12506:
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Thanks for working on this improvement, [~cheersyang]!
One comment for your patch:
{noformat}
public boolean isVolumeEmpty(String volume) throws IOException {
- String dbVolumeRootName = OzoneConsts.KSM_VOLUME_PREFIX + volume;
+ String dbVolumeRootName = OzoneConsts.KSM_VOLUME_PREFIX + volume
+ + OzoneConsts.KSM_BUCKET_PREFIX;
byte[] dbVolumeRootKey = DFSUtil.string2Bytes(dbVolumeRootName);
- // Seek to the root of the volume and look for the next key
- ImmutablePair<byte[], byte[]> volumeRoot =
- store.peekAround(1, dbVolumeRootKey);
- if (volumeRoot != null) {
- String firstBucketKey = DFSUtil.bytes2String(volumeRoot.getKey());
- return !firstBucketKey.startsWith(dbVolumeRootName
- + OzoneConsts.KSM_BUCKET_PREFIX);
+ ImmutablePair<byte[], byte[]>
+ firstBucket = store.peekAround(0, dbVolumeRootKey);
+ if (firstBucket != null) {
+ String firstBucketKey = DFSUtil.bytes2String(firstBucket.getKey());
+ return !firstBucketKey.startsWith(dbVolumeRootName);
}
{noformat}
Why here is {{store.peekAround(0, dbVolumeRootKey);}}? Actually we should find
the right key of dbVolumeRootKey(/#vol/#) and use {{store.peekAround(1,
dbVolumeRootKey)}}, right?
In addition, the following failed UT seem related.
org.apache.hadoop.ozone.ksm.TestKeySpaceManager.testDeleteNonEmptyBucket
org.apache.hadoop.ozone.web.client.TestKeys.testDeleteKey
> 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
>
>
> 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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