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Posted to github@datafusion.apache.org by "lyne7-sc (via GitHub)" <gi...@apache.org> on 2026/05/27 12:40:11 UTC
[PR] fix: LIKE 'prefix%' pruning fails on Utf8View and LargeUtf8 columns [datafusion]
lyne7-sc opened a new pull request, #22562:
URL: https://github.com/apache/datafusion/pull/22562
## Which issue does this PR close?
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- Closes #22561.
## Rationale for this change
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LIKE 'prefix%' predicates on `Utf8View` and `LargeUtf8` columns produce `predicate_evaluation_errors`, causing row group and page index pruning to be skipped entirely.
The cause is `build_like_match` always synthesizes bound literals as `ScalarValue::Utf8`, regardless of the actual column type. When the column is `Utf8View` or `LargeUtf8`, the subsequent comparison between the Utf8-typed bound and the min/max statistics (which use the column's native type) fails with a type mismatch error.
## What changes are included in this PR?
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- Updated `build_like_match` to use `string_literal_as` with the column's data_type() instead of hardcoding `ScalarValue::Utf8` for the lower/upper bound literals.
- Added a regression test (prune_like_prefix) that verifies LIKE prefix pruning works correctly on UTF8 columns with expected row group statistics pruning and zero predicate errors.
## Are these changes tested?
Yes.
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## Are there any user-facing changes?
No.
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Re: [PR] fix: LIKE 'prefix%' pruning fails on Utf8View and LargeUtf8 columns [datafusion]
Posted by "lyne7-sc (via GitHub)" <gi...@apache.org>.
lyne7-sc commented on PR #22562:
URL: https://github.com/apache/datafusion/pull/22562#issuecomment-4560256938
Thank you @alamb
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Re: [PR] fix: LIKE 'prefix%' pruning fails on Utf8View and LargeUtf8 columns [datafusion]
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb commented on code in PR #22562:
URL: https://github.com/apache/datafusion/pull/22562#discussion_r3312274584
##########
datafusion/core/tests/parquet/row_group_pruning.rs:
##########
@@ -2078,3 +2078,26 @@ async fn test_limit_pruning_exceeds_fully_matched() -> datafusion_common::error:
.await;
Ok(())
}
+
+#[tokio::test]
+async fn prune_like_prefix() {
Review Comment:
I verified that this test fails like this without the code chnage
```
thread 'parquet::row_group_pruning::prune_like_prefix' (83571793) panicked at datafusion/core/tests/parquet/row_group_pruning.rs:138:9:
assertion `left == right` failed: mismatched predicate_evaluation error
left: Some(5)
right: Some(0)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```
##########
datafusion/pruning/src/pruning_predicate.rs:
##########
@@ -1816,6 +1817,13 @@ fn extract_string_literal(expr: &Arc<dyn PhysicalExpr>) -> Option<&str> {
None
}
+/// Wrap a string in a `Literal` whose `ScalarValue` matches `target_type`
+fn string_literal_as(value: String, target_type: &DataType) -> Arc<dyn PhysicalExpr> {
+ let utf8 = ScalarValue::Utf8(Some(value));
+ let scalar = try_cast_literal_to_type(&utf8, target_type).unwrap_or(utf8);
Review Comment:
👍
It is sad that this potentially results in a new allocation -- maybe as a follow on PR we can avoid the allocation in `try_cast_literal_to_type`
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Re: [PR] fix: LIKE 'prefix%' pruning fails on Utf8View and LargeUtf8 columns [datafusion]
Posted by "alamb (via GitHub)" <gi...@apache.org>.
alamb merged PR #22562:
URL: https://github.com/apache/datafusion/pull/22562
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