findepi commented on code in PR #14519:
URL: https://github.com/apache/datafusion/pull/14519#discussion_r1946883460
##########
datafusion/core/src/physical_planner.rs:
##########
@@ -689,7 +693,7 @@ impl DefaultPhysicalPlanner {
if physical_field.data_type() !=
logical_field.data_type() {
differences.push(format!("field data type at index
{} [{}]: (physical) {} vs (logical) {}", i, physical_field.name(),
physical_field.data_type(), logical_field.data_type()));
}
- if physical_field.is_nullable() !=
logical_field.is_nullable() {
+ if physical_field.is_nullable() &&
!logical_field.is_nullable() {
Review Comment:
> logical a physical schema can be derived differently and nullable
sometimes derived in different way as well.
agreed, but the earlier delivered schema acts as a contract (promise) for a
later delivered schema
if we told the world that `expr` won't contain null values, we can't change
the mind at physical planning time. it violates the constraint (promise /
contract)
if we told the world that `expr` _may_ contain null values, we didn't
promise that it _will_ contain null values, and we may happen to produce no
null values (and even be aware of that)
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