Jeff Evans created SPARK-31779: ---------------------------------- Summary: Redefining struct inside array incorrectly wraps child fields in array Key: SPARK-31779 URL: https://issues.apache.org/jira/browse/SPARK-31779 Project: Spark Issue Type: Bug Components: SQL Affects Versions: 2.4.5 Reporter: Jeff Evans
It seems that redefining a {{struct}} for the purpose of removing a sub-field, when that {{struct}} is itself inside an {{array}}, results in the remaining (non-removed) {{struct}} fields themselves being incorrectly wrapped in an array. For more context, see [this|https://stackoverflow.com/a/46084983/375670] StackOverflow answer and discussion thread. I have debugged this code and distilled it down to what I believe represents a bug in Spark itself. Consider the following {{spark-shell}} session (version 2.4.5): {code} // use a nested JSON structure that contains a struct inside an array val jsonData = """{ "foo": "bar", "top": { "child1": 5, "child2": [ { "child2First": "one", "child2Second": 2 } ] } }""" // read into a DataFrame val df = spark.read.option("multiline", "true").json(Seq(jsonData).toDS()) // create a new definition for "top", which will remove the "top.child2.child2First" column val newTop = struct(df("top").getField("child1").alias("child1"), array(struct(df("top").getField("child2").getField("child2Second").alias("child2Second"))).alias("child2")) // show the schema before and after swapping out the struct definition df.schema.toDDL // `foo` STRING,`top` STRUCT<`child1`: BIGINT, `child2`: ARRAY<STRUCT<`child2First`: STRING, `child2Second`: BIGINT>>> df.withColumn("top", newTop).schema.toDDL // `foo` STRING,`top` STRUCT<`child1`: BIGINT, `child2`: ARRAY<STRUCT<`child2Second`: ARRAY<BIGINT>>>> {code} Notice in this case that the new definition for {{top.child2.child2Second}} is an {{ARRAY<BIGINT>}}. This is incorrect; it should simply be {{BIGINT}}. There is nothing in the definition of the {{newTop}} {{struct}} that should have caused the type to become wrapped in an array like this. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org