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https://issues.apache.org/jira/browse/IMPALA-12377?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Wenzhe Zhou reassigned IMPALA-12377:
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Assignee: Wenzhe Zhou
> Improve 'select count(*)' for external data source
> --------------------------------------------------
>
> Key: IMPALA-12377
> URL: https://issues.apache.org/jira/browse/IMPALA-12377
> Project: IMPALA
> Issue Type: Sub-task
> Components: Backend, Frontend
> Reporter: Wenzhe Zhou
> Assignee: Wenzhe Zhou
> Priority: Major
>
> The code to handle 'select count(*)' in backend function
> DataSourceScanNode::GetNext() are not efficient. Even there are no column
> data returned from external data source, it still try to materialize rows and
> add rows to RowBatch one by one up to the number of row count. It also call
> GetNextInputBatch() multiple times (count / batch_size), while
> GetNextInputBatch() invoke JNI function.
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