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Fix reordering avro nullable types in MergeHiveSchemaWithAvro #140

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Fix reordering avro nullable types in MergeHiveSchemaWithAvro #140

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9 changes: 9 additions & 0 deletions core/src/main/java/org/apache/iceberg/avro/AvroSchemaUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,15 @@ public static boolean isOptionSchema(Schema schema) {
return false;
}

public static int getNullIndex(Schema schema) {
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@shardulm94 shardulm94 Mar 1, 2023 •
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nullIndexForOptionSchema

Iceberg does not use get in method names. nulls can also be present in complex schemas, so ensure that we add the OptionSchema constraint in the method name itself.

Preconditions.checkArgument(isOptionSchema(schema));
if (schema.getTypes().get(0).getType() == Schema.Type.NULL) {
return 0;
} else {
return 1;
}
}

/**
* This method decides whether a schema represents a single type union, i.e., a union that contains only one option
*
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17 changes: 11 additions & 6 deletions ...k-core/src/main/java/org/apache/iceberg/hivelink/core/schema/MergeHiveSchemaWithAvro.java
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Expand Up @@ -26,6 +26,7 @@
import org.apache.avro.JsonProperties;
import org.apache.avro.LogicalTypes;
import org.apache.avro.Schema;
import org.apache.avro.Schema.Type;
import org.apache.hadoop.hive.serde2.typeinfo.DecimalTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.ListTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.MapTypeInfo;
Expand Down Expand Up @@ -97,12 +98,12 @@ public Schema.Field field(String name, TypeInfo field, Schema.Field partner, Sch
* If the schema is not an option schema or if there is no default value, schema is returned as-is
*/
private Schema reorderOptionIfRequired(Schema schema, Object defaultValue) {
if (AvroSchemaUtil.isOptionSchema(schema) && defaultValue != null) {
boolean isNullFirstOption = schema.getTypes().get(0).getType() == Schema.Type.NULL;
if (isNullFirstOption && defaultValue.equals(JsonProperties.NULL_VALUE)) {
return schema;
if (AvroSchemaUtil.isOptionSchema(schema)) {
int nullIndex = AvroSchemaUtil.getNullIndex(schema);
if (defaultValue != null && !defaultValue.equals(JsonProperties.NULL_VALUE)) {
return Schema.createUnion(schema.getTypes().get(1 - nullIndex), Schema.create(Type.NULL));
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@shardulm94 shardulm94 Mar 1, 2023

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Hey @rzhang10 , I am having a hard time reasoning about these changes. Can you please include a description of how these changes help fix the issue. Can you also update the Java doc of this method with the new changes?

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@shardulm94 shardulm94 Mar 1, 2023 •
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Ok I understand why this is needed. Previously reorderOptionIfRequired only worked correctly when schema was an option schema who first element was null. This was fine because we never returned an option with null as the second element from the children visitors, but now we do. I think the description needs to be updated to reflect the new behavior.

} else {
return Schema.createUnion(schema.getTypes().get(1), schema.getTypes().get(0));
return Schema.createUnion(Schema.create(Type.NULL), schema.getTypes().get(1 - nullIndex));
}
} else {
return schema;
Expand Down Expand Up @@ -143,10 +144,14 @@ public Schema union(UnionTypeInfo union, Schema partner, List<Schema> results) {
@Override
public Schema primitive(PrimitiveTypeInfo primitive, Schema partner) {
boolean shouldResultBeOptional = partner == null || AvroSchemaUtil.isOptionSchema(partner);
int nullIndex = 0;
if (partner != null && AvroSchemaUtil.isOptionSchema(partner)) {
nullIndex = AvroSchemaUtil.getNullIndex(partner);
}
Schema hivePrimitive = hivePrimitiveToAvro(primitive);
// if there was no matching Avro primitive, use the Hive primitive
Schema result = partner == null ? hivePrimitive : checkCompatibilityAndPromote(hivePrimitive, partner);
return shouldResultBeOptional ? AvroSchemaUtil.toOption(result) : result;
return shouldResultBeOptional ? AvroSchemaUtil.toOption(result, nullIndex == 1) : result;
Comment on lines +147 to +154
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@shardulm94 shardulm94 Mar 1, 2023 •
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This handling is incomplete, it only handles cases for primitives inside containers (e.g. list), but does not handle similar cases for nested lists, maps, structs, etc. E.g. this case will fail

  @Test
  public void shouldNotReorderListElementType1() {
    String hive = "struct<fa:array<array<int>>>";
    Schema avro =
            SchemaBuilder.record("r1")
                    .fields()
                    .name("fa")
                    .type()
                    .nullable()
                    .array()
                    .items()
                    .nullable()
                    .array()
                    .items()
                    .nullable()
                    .intType()
                    .arrayDefault(Collections.singletonList(Arrays.asList(1, 2, 3)))
                    .endRecord();

    assertSchema(avro, merge(hive, avro));
  }

I think we need similar handling in other places where we use the shouldResultBeOptional pattern, e.g. in the struct, list and map methods. Might be good to refactor the common pattern into a separate method for reuse.

}

private Schema checkCompatibilityAndPromote(Schema schema, Schema partner) {
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20 changes: 20 additions & 0 deletions ...link-core/src/test/java/org/apache/iceberg/hivelink/core/TestMergeHiveSchemaWithAvro.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
import java.util.stream.Collectors;
import org.apache.avro.LogicalTypes;
import org.apache.avro.Schema;
import org.apache.avro.SchemaBuilder;
import org.apache.avro.util.internal.JacksonUtils;
import org.apache.hadoop.hive.serde2.typeinfo.StructTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfoFactory;
Expand Down Expand Up @@ -355,6 +356,25 @@ public void shouldRecoverLogicalType() {
AvroSchemaUtil.toIceberg(merged);
}

@Test
public void shouldNotReorderListElementType() {
String hive = "struct<fa:array<int>>";
Schema avro =
SchemaBuilder.record("r1")
.fields()
.name("fa")
.type()
.nullable()
.array()
.items()
.nullable()
.intType()
.arrayDefault(Arrays.asList(1, 2, 3))
.endRecord();

assertSchema(avro, merge(hive, avro));
}

// TODO: tests to retain schema props
// TODO: tests for explicit type compatibility check between hive and avro primitives, once we implement it
// TODO: tests for error case => default value in Avro does not match with type from hive
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