mihaibudiu commented on code in PR #4897:
URL: https://github.com/apache/calcite/pull/4897#discussion_r3358905160
##########
core/src/main/java/org/apache/calcite/rel/core/Intersect.java:
##########
@@ -79,4 +82,12 @@ protected Intersect(RelInput input) {
dRows *= 0.25;
return dRows;
}
+
+ @Override protected RelDataType deriveRowType() {
Review Comment:
why "refine" not simply "derive"?
##########
core/src/main/java/org/apache/calcite/sql/type/ReturnTypes.java:
##########
@@ -608,6 +608,81 @@ public static SqlCall stripSeparator(SqlCall call) {
.leastRestrictive(opBinding.collectOperandTypes());
}
+ /**
+ * Refines the nullability of {@code base} using INTERSECT semantics: a
+ * column is NOT NULL if it is NOT NULL in at least one of the
+ * {@code inputTypes} (AND-semantics across inputs).
+ */
+ public static RelDataType refineNullabilityForIntersect(
+ RelDataTypeFactory typeFactory,
+ RelDataType base,
+ List<RelDataType> inputTypes) {
+ final RelDataTypeFactory.Builder builder =
+ new RelDataTypeFactory.Builder(typeFactory);
+ final List<RelDataTypeField> outputFields = base.getFieldList();
+ for (int i = 0; i < outputFields.size(); i++) {
+ boolean nullable = true;
+ for (RelDataType inputType : inputTypes) {
+ nullable &= inputType.getFieldList().get(i).getType().isNullable();
+ }
+ builder.add(outputFields.get(i)).nullable(nullable);
+ }
+ return builder.build();
+ }
+
+ /**
+ * Type-inference strategy for INTERSECT. Computes the least restrictive row
+ * type across all inputs, then refines nullability: a column is NOT NULL if
+ * it is NOT NULL in at least one input (AND semantics across inputs).
Review Comment:
AND should be quoted `"AND"` here and in other comments
##########
core/src/test/java/org/apache/calcite/test/RelBuilderTest.java:
##########
@@ -2577,6 +2707,55 @@ private static RelNode groupIdRel(RelBuilder builder,
boolean extra) {
assertThat(root, hasTree(expected));
}
+ @ParameterizedTest
Review Comment:
how about a test with a ROW field type?
the behavior of nulls with ROW types in Calcite is very strange.
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