[
https://issues.apache.org/jira/browse/SPARK-27027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16783478#comment-16783478
]
Gabor Somogyi commented on SPARK-27027:
---------------------------------------
What I've found is really interesting.
The following test:
{code:java}
test("should print wrong result") {
val df = Seq((1, "John Doe", 30), (2, "Mary Jane", 25), (3, "Josh Duke",
50)).toDF("id", "name", "age")
val dfStruct = df.withColumn("value", struct("name","age"))
val dfKV = dfStruct.select(to_avro('id).as("key"),
to_avro('value).as("value"))
val expectedSchema = StructType(Seq(StructField("name", StringType,
true),StructField("age", IntegerType, false)))
val avroTypeStruct = SchemaConverters.toAvroType(expectedSchema).toString
val avroTypeStr = s"""
|{
| "type": "int",
| "name": "key"
|}
""".stripMargin
dfKV.select(from_avro('key, avroTypeStr)).show
dfKV.select(from_avro('value, avroTypeStruct)).show
}
{code}
prints out the following result on v2.4.0 branch:
{code:java}
+-------------------+
|from_avro(key, int)|
+-------------------+
| 1|
| 2|
| 3|
+-------------------+
+---------------------------------------------+
|from_avro(value, struct<name:string,age:int>)|
+---------------------------------------------+
| [John Doe, 30]|
| [Mary Jane, 25]|
| [Josh Duke, 50]|
+---------------------------------------------+
{code}
When I've tried the exact same stuff with:
{code:java}
spark-shell --packages org.apache.spark:spark-avro_2.11:2.4.0
{code}
then it fails:
{code:java}
scala> spark.version
res0: String = 2.4.0
scala> val df = Seq((1, "John Doe", 30), (2, "Mary Jane", 25), (3, "Josh
Duke", 50)).toDF("id", "name", "age")
df: org.apache.spark.sql.DataFrame = [id: int, name: string ... 1 more field]
scala> val dfStruct = df.withColumn("value", struct("name","age"))
dfStruct: org.apache.spark.sql.DataFrame = [id: int, name: string ... 2 more
fields]
scala> import org.apache.spark.sql.avro._
import org.apache.spark.sql.avro._
scala> val dfKV = dfStruct.select(to_avro('id).as("key"),
to_avro('value).as("value"))
dfKV: org.apache.spark.sql.DataFrame = [key: binary, value: binary]
scala> import org.apache.spark.sql.types._
import org.apache.spark.sql.types._
scala> val expectedSchema = StructType(Seq(StructField("name", StringType,
true),StructField("age", IntegerType, false)))
expectedSchema: org.apache.spark.sql.types.StructType =
StructType(StructField(name,StringType,true),
StructField(age,IntegerType,false))
scala> val avroTypeStruct =
SchemaConverters.toAvroType(expectedSchema).toString
avroTypeStruct: String =
{"type":"record","name":"topLevelRecord","fields":[{"name":"name","type":["string","null"]},{"name":"age","type":"int"}]}
scala> val avroTypeStr = s"""
| |{
| | "type": "int",
| | "name": "key"
| |}
| """.stripMargin
avroTypeStr: String =
"
{
"type": "int",
"name": "key"
}
"
scala> import org.apache.spark.sql.avro.from_avro
import org.apache.spark.sql.avro.from_avro
scala> dfKV.select(from_avro('key, avroTypeStr)).show
+-------------------+
|from_avro(key, int)|
+-------------------+
| 1|
| 2|
| 3|
+-------------------+
scala> dfKV.select(from_avro('value, avroTypeStruct)).show
+---------------------------------------------+
|from_avro(value, struct<name:string,age:int>)|
+---------------------------------------------+
| [Josh Duke, 50]|
| [Josh Duke, 50]|
| [Josh Duke, 50]|
+---------------------------------------------+
{code}
> from_avro function does not deserialize the Avro record of a struct column
> type correctly
> -----------------------------------------------------------------------------------------
>
> Key: SPARK-27027
> URL: https://issues.apache.org/jira/browse/SPARK-27027
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.4.0
> Reporter: Hien Luu
> Priority: Minor
>
> {{from_avro}} function produces wrong output of a struct field. See the
> output at the bottom of the description
> {code}
> import org.apache.spark.sql.types._
> import org.apache.spark.sql.avro._
> import org.apache.spark.sql.functions._
> spark.version
> val df = Seq((1, "John Doe", 30), (2, "Mary Jane", 25), (3, "Josh Duke",
> 50)).toDF("id", "name", "age")
> val dfStruct = df.withColumn("value", struct("name","age"))
> dfStruct.show
> dfStruct.printSchema
> val dfKV = dfStruct.select(to_avro('id).as("key"),
> to_avro('value).as("value"))
> val expectedSchema = StructType(Seq(StructField("name", StringType,
> true),StructField("age", IntegerType, false)))
> val avroTypeStruct = SchemaConverters.toAvroType(expectedSchema).toString
> val avroTypeStr = s"""
> |{
> | "type": "int",
> | "name": "key"
> |}
> """.stripMargin
> dfKV.select(from_avro('key, avroTypeStr)).show
> dfKV.select(from_avro('value, avroTypeStruct)).show
> // output for the last statement and that is not correct
> +---------------------------------------------+
> |from_avro(value, struct<name:string,age:int>)|
> +---------------------------------------------+
> | [Josh Duke, 50]|
> | [Josh Duke, 50]|
> | [Josh Duke, 50]|
> +---------------------------------------------+
> {code}
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