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Posted to issues-all@impala.apache.org by "Wenzhe Zhou (Jira)" <ji...@apache.org> on 2023/08/17 18:36:00 UTC

[jira] [Assigned] (IMPALA-12377) Improve 'select count(*)' for external data source

     [ https://issues.apache.org/jira/browse/IMPALA-12377?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Wenzhe Zhou reassigned IMPALA-12377:
------------------------------------

    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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