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Posted to jira@arrow.apache.org by "Andy Grove (Jira)" <ji...@apache.org> on 2020/12/22 23:24:00 UTC

[jira] [Assigned] (ARROW-10995) [Rust] [DataFusion] Improve parallelism when reading Parquet files

     [ https://issues.apache.org/jira/browse/ARROW-10995?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Grove reassigned ARROW-10995:
----------------------------------

    Assignee: Andy Grove

> [Rust] [DataFusion] Improve parallelism when reading Parquet files
> ------------------------------------------------------------------
>
>                 Key: ARROW-10995
>                 URL: https://issues.apache.org/jira/browse/ARROW-10995
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: Rust - DataFusion
>            Reporter: Andy Grove
>            Assignee: Andy Grove
>            Priority: Major
>
> Currently the unit of parallelism is the number of parquet files being read.
> For example, if we run a query against a Parquet table that consists of 8 partitions then we will attempt to run 8 async tasks in parallel and if there is a single Parquet file then we will only try and run 1 async task so this does not scale well.
> A better approach would be to have one parallel task per "chunk" in each parquet file. This would involve an upfront step in the planner to scan the parquet meta-data to get a list of chunks and then split these up between the configured number of parallel tasks.
>  
>  



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