morrySnow commented on code in PR #69074:
URL: https://github.com/apache/doris/pull/69074#discussion_r4272010637
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fe/fe-core/src/main/java/org/apache/doris/nereids/rules/rewrite/AdjustNullable.java:
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@@ -289,25 +291,61 @@ public Plan visitLogicalSetOperation(LogicalSetOperation
setOperation, Map<ExprI
ImmutableList.Builder<List<SlotReference>> newChildrenOutputs =
ImmutableList.builder();
List<Boolean> inputNullable = null;
if (!setOperation.children().isEmpty()) {
- inputNullable =
Lists.newArrayListWithCapacity(setOperation.getOutputs().size());
- for (int i = 0; i < setOperation.getOutputs().size(); i++) {
- inputNullable.add(false);
+ // whether the output column can be null depends on the semantics
of the set operation:
+ // - union: a row is in the result if it appears in any child, so
the column can be null if any
+ // child column can be null;
+ // - intersect: a row is in the result only if it appears in every
child, so the column can be
+ // null only if every child column can be null;
+ // - except: the result is a subset of the left child(child(0)),
so the column can be null only
Review Comment:
但是 LogicalSetOperation里面不是这么计算的，所以这里真的应该这么改吗？另外，这个逻辑和BE是对齐的吗？
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