Describe the bug
When a non-pushable (KeepInPlace) function call appears once bare and once wrapped in get_field(...),
CommonSubexprEliminate correctly deduplicates the bare occurrence into a __common_expr_N column — but leaf-expression pushdown (ExtractLeafExpressions / PushDownLeafProjections) then re-derives the full original call a second time when it tries to push the get_field expression down, because __common_expr_N's Column reference is indistinguishable, at the ExpressionPlacement level, from a genuine cheap base-table column.
Net effect: the function is evaluated twice instead of once.
To Reproduce
Using here the arrow_field UDF as an example since this function returns a struct type.
CREATE TABLE t (a INT) AS VALUES (1), (2);
EXPLAIN SELECT
CASE WHEN arrow_field(a) IS NOT NULL
THEN get_field(arrow_field(a), 'name') END AS c1
FROM t; Actual physical plan
+---------------+-------------------------------+
| plan_type | plan |
+---------------+-------------------------------+
| physical_plan | ┌───────────────────────────┐ |
| | │ ProjectionExec │ |
| | │ -------------------- │ |
| | │ c1: │ |
| | │ CASE WHEN arrow_field(a) │ |
| | │ IS NOT NULL THEN │ |
| | │ get_field │ |
| | │ (arrow_field(a), │ |
| | │ name) END │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ DataSourceExec │ |
| | │ -------------------- │ |
| | │ bytes: 112 │ |
| | │ format: memory │ |
| | │ rows: 1 │ |
| | └───────────────────────────┘ |
| | |
+---------------+-------------------------------+
The function (arrow_field) is called twice.
Expected behavior
Expected physical plan
+---------------+-------------------------------+
| plan_type | plan |
+---------------+-------------------------------+
| physical_plan | ┌───────────────────────────┐ |
| | │ ProjectionExec │ |
| | │ -------------------- │ |
| | │ c1: │ |
| | │ CASE WHEN __common_expr_1 │ |
| | │ IS NOT NULL THEN │ |
| | │ get_field │ |
| | │ (__common_expr_1, │ |
| | │ name) END │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ ProjectionExec │ |
| | │ -------------------- │ |
| | │ __common_expr_1: │ |
| | │ arrow_field(a) │ |
| | └─────────────┬─────────────┘ |
| | ┌─────────────┴─────────────┐ |
| | │ DataSourceExec │ |
| | │ -------------------- │ |
| | │ bytes: 112 │ |
| | │ format: memory │ |
| | │ rows: 1 │ |
| | └───────────────────────────┘ |
| | |
+---------------+-------------------------------+
The function (arrow_field) is called once;
get_field references the shared __common_expr_1 column.
Additional context
No response
Describe the bug
When a non-pushable (
KeepInPlace) function call appears once bare and once wrapped inget_field(...),CommonSubexprEliminatecorrectly deduplicates the bare occurrence into a__common_expr_Ncolumn — but leaf-expression pushdown (ExtractLeafExpressions/PushDownLeafProjections) then re-derives the full original call a second time when it tries to push theget_fieldexpression down, because__common_expr_N's Column reference is indistinguishable, at theExpressionPlacementlevel, from a genuine cheap base-table column.Net effect: the function is evaluated twice instead of once.
To Reproduce
Using here the
arrow_fieldUDF as an example since this function returns a struct type.Actual physical plan
The function (arrow_field) is called twice.
Expected behavior
Expected physical plan
The function (arrow_field) is called once;
get_fieldreferences the shared__common_expr_1column.Additional context
No response