github-actions[bot] commented on code in PR #65591:
URL: https://github.com/apache/doris/pull/65591#discussion_r3612931048
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fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/AccessPathExpressionCollector.java:
##########
@@ -334,6 +338,23 @@ public Void visitElementAt(ElementAt elementAt,
CollectorContext context) {
Expression fieldName = arguments.get(1);
DataType fieldType = fieldName.getDataType();
if (fieldName.isLiteral() && (fieldType.isIntegerLikeType() ||
fieldType.isStringLikeType())) {
+ // element_at(s, 'field') IS NULL has two-layer null semantics:
+ // s IS NULL OR s.field IS NULL
+ // Always emit META [s, NULL] for the struct-level null map.
+ // Only emit META [s, field, NULL] when the selected field
itself is nullable.
+ if (context.type == ColumnAccessPathType.META
+ &&
isUnderIsNull(context.accessPathBuilder.getPathList())) {
+ StructField field = resolveStructField(
+ (StructType) first.getDataType(), fieldName);
+ // Path 1: struct-level null check — bypass field prefix
+ continueCollectAccessPath(first, copyContext(context));
Review Comment:
[P1] Do not map expression nullability to a non-null Struct
This unconditional ancestor walk can emit a physical NULL path for a node
that has no null map. With `s STRUCT<f:INT NOT NULL> NOT NULL`, a
predicate-only `element_at(s, 'f') IS NULL` emits only typed META `[s,NULL]`:
`ElementAt` is always nullable, then the non-nullable-field branch returns
early. The same happens through `element_at(if(id = 1, NULL, s), 'f')`, where
synthetic `IF` nullability is forwarded to the physical `s` slot. The BE makes
the root Struct `NULL_MAP_ONLY`, but this slot creates a plain `ColumnStruct`,
so `StructFileColumnIterator::next_batch` fails its `is_column_nullable(*dst)`
check. This is distinct from the existing nullable-parent/non-nullable-leaf
thread: the current fix redirects that case to a real parent null map, whereas
these paths target a root with no map. Please track physical nullability
through the ancestor/wrapper path and retain DATA (or disable metadata pruning)
when no real null map can answer the expression; add direct and IF-wrapped all-
NOT-NULL regressions.
##########
fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/AccessPathExpressionCollector.java:
##########
@@ -334,6 +338,23 @@ public Void visitElementAt(ElementAt elementAt,
CollectorContext context) {
Expression fieldName = arguments.get(1);
DataType fieldType = fieldName.getDataType();
if (fieldName.isLiteral() && (fieldType.isIntegerLikeType() ||
fieldType.isStringLikeType())) {
+ // element_at(s, 'field') IS NULL has two-layer null semantics:
+ // s IS NULL OR s.field IS NULL
+ // Always emit META [s, NULL] for the struct-level null map.
+ // Only emit META [s, field, NULL] when the selected field
itself is nullable.
+ if (context.type == ColumnAccessPathType.META
+ &&
isUnderIsNull(context.accessPathBuilder.getPathList())) {
+ StructField field = resolveStructField(
+ (StructType) first.getDataType(), fieldName);
+ // Path 1: struct-level null check — bypass field prefix
+ continueCollectAccessPath(first, copyContext(context));
+ if (field != null && !field.isNullable()) {
+ // Non-nullable leaf: struct-level NULL is sufficient
+ return null;
Review Comment:
[P1] Keep the field referenced by the unchanged predicate
The early return drops a field that the filter expression still references.
For the reduced plan
```text
Project(element_at(s, 'g'))
Filter(element_at(s, 'f') IS NULL)
Scan(s STRUCT<f:INT NOT NULL,g:INT> NULL)
```
the projection records DATA `[s,g]`, line 350 records META `[s,NULL]`, and
this branch returns without any `f` path. Because the Struct now has a parent
NULL path plus a partial child, `DataTypeAccessTree.pruneDataType` produces
`STRUCT<g>`. `SlotTypeReplacer` then rebuilds the unchanged filter on that
pruned slot with signature reuse disabled, so `ElementAt.structFieldType`
cannot find `f` (and the materialized Struct could not evaluate it either). A
parent null map is a valid semantic shortcut only if the predicate is also
rewritten to test the parent; otherwise preserve `f` in the pruned type/data
paths. Please add nullable-root sibling-projection regressions for both `IS
NULL` and `IS NOT NULL`.
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