sadikovi commented on code in PR #42618:
URL: https://github.com/apache/spark/pull/42618#discussion_r1302362345
##########
connector/avro/src/main/scala/org/apache/spark/sql/avro/SchemaConverters.scala:
##########
@@ -142,18 +143,30 @@ object SchemaConverters {
if (avroSchema.getTypes.asScala.exists(_.getType == NULL)) {
// In case of a union with null, eliminate it and make a recursive
call
val remainingUnionTypes = AvroUtils.nonNullUnionBranches(avroSchema)
- if (remainingUnionTypes.size == 1) {
- toSqlTypeHelper(remainingUnionTypes.head, existingRecordNames,
avroOptions)
- .copy(nullable = true)
- } else {
- toSqlTypeHelper(
- Schema.createUnion(remainingUnionTypes.asJava),
- existingRecordNames,
- avroOptions).copy(nullable = true)
- }
+ toSqlTypeHelper(
+ Schema.createUnion(remainingUnionTypes.asJava),
+ existingRecordNames,
+ avroOptions).copy(nullable = true)
} else avroSchema.getTypes.asScala.map(_.getType).toSeq match {
case Seq(t1) =>
- toSqlTypeHelper(avroSchema.getTypes.get(0), existingRecordNames,
avroOptions)
+ // If spark.sql.avro.alwaysConvertUnionToStructType is set to
false (default),
+ // we convert Avro union with a single primitive type into a
primitive Spark type
+ // instead of a StructType.
+ if (!SQLConf.get.avroAlwaysConvertUnionToStruct) {
+ toSqlTypeHelper(avroSchema.getTypes.get(0), existingRecordNames,
avroOptions)
Review Comment:
I was going to suggest doing this for Avro schema converter in the Avro data
source where this is required because the top schema is always expected to be a
struct.
For example, we change this code in AvroUtils:
```scala
SchemaConverters.toSqlType(avroSchema, options).dataType match {
case t: StructType => Some(t)
case _ => throw new RuntimeException(
s"""Avro schema cannot be converted to a Spark SQL StructType:
|
|${avroSchema.toString(true)}
|""".stripMargin)
}
```
to something like this:
```scala
SchemaConverters.toSqlType(avroSchema, options).dataType match {
case t: StructType => Some(t)
case t: AtomicType => StructType(StructField("value", t, nullable = true))
case _ => throw new RuntimeException(
s"""Avro schema cannot be converted to a Spark SQL StructType:
|
|${avroSchema.toString(true)}
|""".stripMargin)
}
```
Can we also check that this change will not affect `from_avro` SQL function?
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