[GitHub] [arrow-datafusion] alamb commented on a change in pull request #519: 110 support group by positions

[GitBox <gi...@apache.org>]

alamb commented on a change in pull request #519:
URL: https://github.com/apache/arrow-datafusion/pull/519#discussion_r646670864



##########
File path: datafusion/src/sql/utils.rs
##########
@@ -390,6 +391,29 @@ pub(crate) fn extract_aliases(exprs: &[Expr]) -> HashMap<String, Expr> {
         .collect::<HashMap<String, Expr>>()
 }
 
+pub(crate) fn resolve_positions_to_exprs(
+    expr: &Expr,
+    select_exprs: &[Expr],
+) -> Result<Expr> {
+    match expr {
+        // sql_expr_to_logical_expr maps number to i64
+        // https://github.com/apache/arrow-datafusion/blob/8d175c759e17190980f270b5894348dc4cff9bbf/datafusion/src/sql/planner.rs#L882-L887
+        Expr::Literal(ScalarValue::Int64(Some(pos))) => {

Review comment:
       I left some suggestions for tests which I think will help cover this case as well

##########
File path: datafusion/src/sql/planner.rs
##########
@@ -2319,6 +2320,16 @@ mod tests {
         );
     }
 
+    #[test]
+    fn select_simple_aggregate_with_groupby_can_use_positions() {
+        quick_test(
+            "SELECT state, age AS b, COUNT(1) FROM person GROUP BY 1, 2",
+            "Projection: #state, #age AS b, #COUNT(UInt8(1))\
+             \n  Aggregate: groupBy=[[#state, #age]], aggr=[[COUNT(UInt8(1))]]\
+             \n    TableScan: person projection=None",
+        );
+    }

Review comment:
       Can you also please add the following tests:
   
   1. A test that groups in an order other than written, for example,  `SELECT state, age AS b, COUNT(1) FROM person GROUP BY 2,1 `?
   2. A test that has an invalid group index. for example,  `SELECT state, age AS b, COUNT(1) FROM person GROUP BY 5`?
   3. A test that where the index is not valid at all, for example:  `SELECT state, age AS b, COUNT(1) FROM person GROUP BY 0`?

##########
File path: datafusion/src/sql/utils.rs
##########
@@ -390,6 +391,29 @@ pub(crate) fn extract_aliases(exprs: &[Expr]) -> HashMap<String, Expr> {
         .collect::<HashMap<String, Expr>>()
 }
 
+pub(crate) fn resolve_positions_to_exprs(
+    expr: &Expr,

Review comment:
       You can probably save a clone here by passing in `expr` directly (rather than a reference)




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