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https://issues.apache.org/jira/browse/KYLIN-2506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15925589#comment-15925589
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Billy Liu commented on KYLIN-2506:
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I understand the cube can have only one segment.
The user I mentioned before, is the query user, not model designer, or cube
builder. Sorry for the ambiguous. So the segment is transparent to them. My
point here is that the TrieDictionary used for precises count does not have
much benefits but introduces more complexity. So suggest leaving
GlobalDictinary only for precise count.
> Refactor Global Dictionary
> --------------------------
>
> Key: KYLIN-2506
> URL: https://issues.apache.org/jira/browse/KYLIN-2506
> Project: Kylin
> Issue Type: Improvement
> Components: General
> Affects Versions: v2.0.0
> Reporter: kangkaisen
> Assignee: kangkaisen
> Fix For: v2.0.0
>
>
> The main points of this refactor:
> 1 Fix the bug that the RemoveListener of LoadingCache swallowed any
> exceptions when building the GlobalDict.
> 2 Fix the bug that the HDFS filename of DictSliceKey had Illegal characters.
> 3 Fix the bug that the HDFS filename of DictSliceKey maybe longer than 255.
> 4 Fix the bug that DictNode split failed if value length greater than 255
> bytes.
> 5 Decouple the build and query of GlobalDict:
> Abstract the builder of AppendTrieDictionary to AppendTrieDictionaryBuilder;
> Add LoadingCache to AppendTrieDictionary and make AppendTrieDictionary is
> only readable.
> 6 Remove dependence of LoadingCache when building the GlobalDict.
> 7 Abstract the HDFS operations to GlobalDictStore.
> 8 Abstract the metadata of GlobalDict to GlobalDictMetadata.
> 9 Delete CachedTreeMap.
> 10 Remove the support of multithreading concurrent build and I will add
> distributed lock for GlobalDict later.
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