[jira] [Updated] (ARROW-8902) [rust][datafusion] optimize count(*) queries on parquet sources
[ https://issues.apache.org/jira/browse/ARROW-8902?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Paddy Horan updated ARROW-8902: --- Component/s: Rust > [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: Improvement > Components: Rust, Rust - DataFusion >Reporter: Alex Gaynor >Priority: Minor > > 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)
[jira] [Updated] (ARROW-8902) [rust][datafusion] optimize count(*) queries on parquet sources
[ https://issues.apache.org/jira/browse/ARROW-8902?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Paddy Horan updated ARROW-8902: --- Issue Type: Improvement (was: Bug) > [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: Improvement > Components: Rust - DataFusion >Reporter: Alex Gaynor >Priority: Minor > > 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)
