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https://issues.apache.org/jira/browse/KYLIN-3491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16575986#comment-16575986
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Zhong Yanghong commented on KYLIN-3491:
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For a dimension with cardinality around 90M, the comparison of encoding
performance is as follows:
* Directly using global dictionary, 165min
* Using two steps with shrunken dictionary, 35+11=46min
> Improve the cube building process when using global dictionary
> --------------------------------------------------------------
>
> Key: KYLIN-3491
> URL: https://issues.apache.org/jira/browse/KYLIN-3491
> Project: Kylin
> Issue Type: Improvement
> Reporter: Zhong Yanghong
> Assignee: Zhong Yanghong
> Priority: Major
>
> By current cubing process, if the global dictionary is very large, since the
> raw data records are unsorted, it's hard to encode raw values into ids for
> the input of bitmap due to frequent swap of the dictionary slices. We need a
> refined process. The idea is as follows:
> # for each source data block, there will be a mapper generating the distinct
> values & sort them
> # encode the sorted distinct values and generate a shrunken dict for each
> source data block.
> # when building base cuboid, use the shrunken dict for each source data
> block for encoding.
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