Andy Grove created ARROW-10995:
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Summary: [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
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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