dramaticlly commented on code in PR #17513:
URL: https://github.com/apache/iceberg/pull/17513#discussion_r3716012064
##########
api/src/main/java/org/apache/iceberg/types/TypeUtil.java:
##########
@@ -291,6 +291,28 @@ public static List<Types.NestedField>
ancestorFields(Schema schema, int fieldId)
return parents;
}
+ /**
+ * Returns whether a field can evaluate to null within the given schema.
+ *
+ * <p>A field can be null if it is declared optional, or if it is nested
inside an optional field.
+ * For example, a required field inside an optional struct is effectively
null whenever that
+ * struct is null.
+ *
+ * <p>If the field is not present in the schema, this method returns true
because its nullability
+ * cannot be determined.
+ *
+ * @param schema The schema that contains the field ID
+ * @param fieldId The field ID to check
+ * @return true if the field may be null, false if it cannot be null
+ */
+ public static boolean isNullable(Schema schema, int fieldId) {
+ Types.NestedField field = schema.findField(fieldId);
+
+ return field == null
+ || field.isOptional()
+ || ancestorFields(schema,
fieldId).stream().anyMatch(Types.NestedField::isOptional);
Review Comment:
ancestorFields calls `TypeUtil.indexParents` for each invocation and ends up
traverse the schema tree. I am wondering if worth caching the indexParents in
Schema. Currently it's only used for identifier field in constructor and
discarded right after
https://github.com/apache/iceberg/blob/1d8c71529e0013bb57716451a67dcd284ea35965/api/src/main/java/org/apache/iceberg/Schema.java#L153
##########
api/src/test/java/org/apache/iceberg/types/TestTypeUtil.java:
##########
@@ -972,6 +972,151 @@ public void ancestorFieldsInNestedSchema() {
assertThat(TypeUtil.ancestorFields(schema,
17)).containsExactly(pointsElement, points);
}
+ @Test
+ public void isNullableWithUnknownFieldId() {
+ Schema schema = new Schema(required(1, "id", IntegerType.get()));
+
+ assertThat(TypeUtil.isNullable(schema, 2)).isTrue();
Review Comment:
can we try the empty schema as well? `isNullable(new Schema(), 1)`
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