Alex Gaynor created ARROW-8902: ---------------------------------- Summary: [rust][datafusion] optimize count(*) queries on parquet sources Key: ARROW-8902 URL: https://issues.apache.org/jira/browse/ARROW-8902 Project: Apache Arrow Issue Type: Bug Components: Rust - DataFusion Reporter: Alex Gaynor
Currently, as far as I can tell, when you perform a `select count(*) from dataset` in datafusion against a parquet dataset, the way this is implemented is by doing a scan on column 0, and counting up all of the rows (specifically I think it counts the # of rows in each batch). However, for the specific case of just counting _everythign_ in a parquet file, you can just read the rowcount from the footer metadata, so it's O(1) instead of O(n) -- This message was sent by Atlassian Jira (v8.3.4#803005)