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https://issues.apache.org/jira/browse/SPARK-24438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16536682#comment-16536682
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Marco Gaido edited comment on SPARK-24438 at 7/9/18 8:37 AM:
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IIRC, Hive has a placeholder string (\_\_HIVE_DEFAULT_PARTITION\_\_) for null
value in partitions.
was (Author: mgaido):
IIRC, Hive has a placeholder string (__HIVE_DEFAULT_PARTITION__) for null value
in partitions.
> Empty strings and null strings are written to the same partition
> ----------------------------------------------------------------
>
> Key: SPARK-24438
> URL: https://issues.apache.org/jira/browse/SPARK-24438
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.3.0
> Reporter: Mukul Murthy
> Priority: Major
>
> When you partition on a string column that has empty strings and nulls, they
> are both written to the same default partition. When you read the data back,
> all those values get read back as null.
> {code:java}
> import org.apache.spark.sql.types._
> import org.apache.spark.sql.catalyst.encoders.RowEncoder
> val data = Seq(Row(1, ""), Row(2, ""), Row(3, ""), Row(4, "hello"), Row(5,
> null))
> val schema = new StructType().add("a", IntegerType).add("b", StringType)
> val df = spark.createDataFrame(spark.sparkContext.parallelize(data), schema)
> display(df)
> =>
> a b
> 1
> 2
> 3
> 4 hello
> 5 null
> df.write.mode("overwrite").partitionBy("b").save("/home/mukul/weird_test_data4")
> val df2 = spark.read.load("/home/mukul/weird_test_data4")
> display(df2)
> =>
> a b
> 4 hello
> 3 null
> 2 null
> 1 null
> 5 null
> {code}
> Seems to affect multiple types of tables.
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