laserninja opened a new issue, #16032:
URL: https://github.com/apache/iceberg/issues/16032
### Feature Request / Improvement
### Apache Iceberg version
main (unreleased)
### Query engine
Any (Spark, Flink, etc.)
### Problem
`ParquetFilters.convert()` has a TODO on line 45 acknowledging that
`AlwaysFalse.INSTANCE` is not handled:
```java
// TODO: handle AlwaysFalse.INSTANCE
if (pred != null && pred != AlwaysTrue.INSTANCE) {
return FilterCompat.get(pred);
} else {
return FilterCompat.NOOP;
}
```
When an Iceberg expression evaluates to `AlwaysFalse`, the visitor returns
`AlwaysFalse.INSTANCE` — a custom `FilterPredicate` sentinel. Because it is
non-null and not `AlwaysTrue.INSTANCE`, the condition passes and it gets
wrapped via `FilterCompat.get(pred)`. Parquet's internal filter infrastructure
has no knowledge of Iceberg's `AlwaysFalse` type, so the resulting filter
behavior is undefined — it may read all rows instead of none.
### Expected behavior
When the expression evaluates to `AlwaysFalse`, the convert method should
either:
- Return a filter that rejects all row groups (e.g., via a tautologically
false Parquet predicate), or
- Return `FilterCompat.NOOP` and let Iceberg's own row-group filtering
handle the exclusion
### Proposed fix
Add `AlwaysFalse.INSTANCE` to the condition:
```java
if (pred != null && pred != AlwaysTrue.INSTANCE && pred !=
AlwaysFalse.INSTANCE) {
return FilterCompat.get(pred);
} else if (pred == AlwaysFalse.INSTANCE) {
// construct a false predicate or signal no rows
} else {
return FilterCompat.NOOP;
}
```
### Affected file
ParquetFilters.java (line 45–50)
### Query engine
None
### Willingness to contribute
- [x] I can contribute this improvement/feature independently
- [ ] I would be willing to contribute this improvement/feature with
guidance from the Iceberg community
- [ ] I cannot contribute this improvement/feature at this time
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