funcheetah commented on code in PR #4242:
URL: https://github.com/apache/iceberg/pull/4242#discussion_r854343442
##########
core/src/main/java/org/apache/iceberg/avro/AvroSchemaUtil.java:
##########
@@ -154,6 +154,27 @@ public static boolean isOptionSchema(Schema schema) {
return false;
}
+ /**
+ * This method decides whether a schema is of type union and is complex
union and is optional
+ *
+ * Complex union: the number of options in union not equals to 2
+ * Optional: null is present in union
+ *
+ * @param schema input schema
+ * @return true if schema is complex union and it is optional
+ */
+ public static boolean isOptionalComplexUnion(Schema schema) {
+ if (schema.getType() == UNION && schema.getTypes().size() != 2) {
Review Comment:
Thanks for catching this. Non-nullable union of single type will be handled
in follow-up PR. Basically, ```[type]``` will be read as ```type``` instead of
```struct<tag, field0>```.
##########
core/src/main/java/org/apache/iceberg/avro/AvroSchemaVisitor.java:
##########
@@ -52,8 +52,21 @@
case UNION:
List<Schema> types = schema.getTypes();
List<T> options = Lists.newArrayListWithExpectedSize(types.size());
- for (Schema type : types) {
- options.add(visit(type, visitor));
+ if (AvroSchemaUtil.isOptionSchema(schema)) {
+ for (Schema type : types) {
+ options.add(visit(type, visitor));
+ }
+ } else {
+ // complex union case
Review Comment:
The union to struct conversion and assigning filed names need to happen
while traversing the schema tree. We put this logic in a separate branch other
than optional union. In addition, the idea is similar to how we handle
```LogicalMap``` as in the code:
```
case ARRAY:
if (schema.getLogicalType() instanceof LogicalMap) {
return visitor.array(schema, visit(schema.getElementType(),
visitor));
} else {
return visitor.array(schema, visitWithName("element",
schema.getElementType(), visitor));
}
```
This branch of code which handles cases other than optional union ```[null,
type]``` is needed. If we remove it, tests will fail. Curious which tests are
you running? I can see the tests failure in both
```TestUnionSchemaConversions``` and ```TestSparkAvroUnions```.
##########
spark/v3.2/spark/src/test/java/org/apache/iceberg/spark/data/TestSparkAvroUnions.java:
##########
@@ -0,0 +1,272 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.iceberg.spark.data;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+import org.apache.avro.SchemaBuilder;
+import org.apache.avro.file.DataFileWriter;
+import org.apache.avro.generic.GenericData;
+import org.apache.avro.generic.GenericDatumWriter;
+import org.apache.iceberg.Files;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.avro.Avro;
+import org.apache.iceberg.avro.AvroIterable;
+import org.apache.iceberg.avro.AvroSchemaUtil;
+import org.apache.iceberg.relocated.com.google.common.collect.Lists;
+import org.apache.spark.sql.catalyst.InternalRow;
+import org.junit.Assert;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+public class TestSparkAvroUnions {
Review Comment:
Thanks for the suggestions. Projection of columns inside a complex union is
not supported yet and will be handled in followup PR. Do you think it is okay
to add tests for columns projection later when it is supported?
##########
core/src/main/java/org/apache/iceberg/avro/AvroSchemaWithTypeVisitor.java:
##########
@@ -79,11 +79,25 @@
private static <T> T visitUnion(Type type, Schema union,
AvroSchemaWithTypeVisitor<T> visitor) {
List<Schema> types = union.getTypes();
List<T> options = Lists.newArrayListWithExpectedSize(types.size());
- for (Schema branch : types) {
- if (branch.getType() == Schema.Type.NULL) {
- options.add(visit((Type) null, branch, visitor));
- } else {
- options.add(visit(type, branch, visitor));
+
+ // simple union case
+ if (AvroSchemaUtil.isOptionSchema(union)) {
+ for (Schema branch : types) {
+ if (branch.getType() == Schema.Type.NULL) {
+ options.add(visit((Type) null, branch, visitor));
+ } else {
+ options.add(visit(type, branch, visitor));
+ }
+ }
+ } else { // complex union case
+ int index = 1;
+ for (Schema branch : types) {
+ if (branch.getType() == Schema.Type.NULL) {
+ options.add(visit((Type) null, branch, visitor));
+ } else {
+ options.add(visit(type.asStructType().fields().get(index).type(),
branch, visitor));
Review Comment:
Replied to the comment to ```AvroSchemaVisitor```, please take a look.
Thanks.
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