zhuqi-lucas commented on code in PR #24638:
URL: https://github.com/apache/datafusion/pull/24638#discussion_r3848922786
##########
datafusion/core/tests/parquet/filter_pushdown.rs:
##########
@@ -746,3 +752,51 @@ impl PredicateCacheTest {
Ok(())
}
}
+
+/// A predicate that is pushed into the parquet decoder and then fails while it
+/// is being evaluated must report the original error, so that callers can
still
+/// tell a user error apart from an internal one.
+#[tokio::test]
+async fn pushed_down_predicate_reports_the_original_error() {
+ let tempdir = TempDir::new_in(Path::new(".")).unwrap();
+ let path = tempdir.path().join("cast_error.parquet");
+
+ let batch = RecordBatch::try_from_iter(vec![(
+ "s",
+ Arc::new(StringArray::from(vec!["not_an_int"])) as ArrayRef,
Review Comment:
Forward-looking nit on test robustness: the file has a single column `s` and
the predicate is also on `s`, so the projection contains **zero** non-filter
columns. That's exactly the shape the narrow-projection pushdown gate being
prototyped in #24426 declines.
No such gate exists on `main` today (only unsupported nested types make
`build()` return `None`), so this passes now. But reading that branch's gate,
this test would not survive it:
```rust
// datasource-parquet/src/source.rs
const PUSHDOWN_MIN_NON_FILTER_COLS: usize = 3;
...
if pushdown_filters && !has_dynamic_filter && mode != Always {
// non_filter_projected = |projected cols| - |filter cols|
if non_filter_projected < PUSHDOWN_MIN_NON_FILTER_COLS {
pushdown_filters = false; // filter goes back to a FilterExec
}
}
```
With no `ORDER BY`/`LIMIT` there is no dynamic filter, so the
`!has_dynamic_filter` guard doesn't exempt this scan; `non_filter_projected` is
0, pushdown is declined, and `assert!(!plan.contains("FilterExec"))` fails.
Note the threshold is 3, so adding one unfiltered column isn't enough — that
still leaves `non_filter_projected = 1`. Surviving that gate would take three
non-filter projected columns (four total). Not blocking, just something to know
if that gate lands.
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