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https://issues.apache.org/jira/browse/KYLIN-3423?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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liyang updated KYLIN-3423:
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Description:
Currently FactDistinctColumnsMapper writes every cell to mapper output. In
spite of mapper side Combiner, we could do better de-dup using available mapper
memory.
The situation becomes worse after KYLIN-3370, because not only dictionary
columns, now it is every dimension column get written as mapper output.
Suggest
* For non-dictionary dimension column, only write min/max value to mapper
output.
was:
Currently FactDistinctColumnsMapper writes every cell to mapper output. In
spite of mapper side Combiner, we could do better de-dup using available mapper
memory.
The situation becomes worse after KYLIN-3370, because not only dictionary
columns, now it is every dimension column get written as mapper output.
Suggest
* Use available mapper memory to de-dup before write to mapper output.
* For non-dictionary dimension column, only write min/max value to mapper
output.
> Performance improvement in FactDistinctColumnsMapper
> ----------------------------------------------------
>
> Key: KYLIN-3423
> URL: https://issues.apache.org/jira/browse/KYLIN-3423
> Project: Kylin
> Issue Type: Improvement
> Reporter: liyang
> Assignee: Shaoxiong Zhan
> Priority: Major
>
> Currently FactDistinctColumnsMapper writes every cell to mapper output. In
> spite of mapper side Combiner, we could do better de-dup using available
> mapper memory.
> The situation becomes worse after KYLIN-3370, because not only dictionary
> columns, now it is every dimension column get written as mapper output.
> Suggest
> * For non-dictionary dimension column, only write min/max value to mapper
> output.
>
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