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https://issues.apache.org/jira/browse/ARROW-9520?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated ARROW-9520:
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Labels: pull-request-available (was: )
> [Rust] [DataFusion] Can't alias an aggregate expression
> -------------------------------------------------------
>
> Key: ARROW-9520
> URL: https://issues.apache.org/jira/browse/ARROW-9520
> Project: Apache Arrow
> Issue Type: Bug
> Components: Rust - DataFusion
> Reporter: Jorge Leitão
> Priority: Major
> Labels: pull-request-available
> Time Spent: 10m
> Remaining Estimate: 0h
>
> The following test (on execute) fails:
> {code}
> #[test]
> fn aggregate_with_alias() -> Result<()> {
> let results = execute("SELECT c1, COUNT(c2) AS count FROM test GROUP
> BY c1", 4)?;
> assert_eq!(field_names(batch), vec!["c1", "count"]);
> let expected = vec!["0,10", "1,10", "2,10", "3,10"];
> let mut rows = test::format_batch(&batch);
> rows.sort();
> assert_eq!(rows, expected);
> Ok(())
> }
> {code}
> The root cause is that, in {{sql::planner}}, we interpret {{COUNT(c2) AS
> count}} as An {{Expr::Alias}}, which fails the {{is_aggregate_expr}}
> condition, thus being interpreted as grouped expression instead of an
> aggregated expression. This raises the Error
> {{General("Projection references non-aggregate values")}}
> The planner could interpret the statement above as two steps: an aggregation
> followed by a projection. Alternatively, we can allow aliases to be valid
> aggregation expressions.
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