GitHub user maropu opened a pull request:
https://github.com/apache/spark/pull/16410
[SPARK-19005][SQL] Keep column ordering when a schema is explicitly
specified
## What changes were proposed in this pull request?
This pr is to keep column ordering when a schema is explicitly specified.
A concrete example is as follows;
```
scala> import org.apache.spark.sql.types._
scala> case class A(a: Long, b: Int)
scala> val as = Seq(A(1, 2))
scala>
spark.createDataFrame(as).write.parquet("/Users/maropu/Desktop/data/a=1/")
scala> val df = spark.read.parquet("/Users/maropu/Desktop/data/")
scala> df.printSchema
root
|-- a: integer (nullable = true)
|-- b: integer (nullable = true)
scala> val schema = new StructType().add("a", LongType).add("b",
IntegerType)
scala> val df =
spark.read.schema(schema).parquet("/Users/maropu/Desktop/data/")
scala> df.printSchema
root
|-- b: integer (nullable = true)
|-- a: long (nullable = true)
```
This fix removes the code to filter out the overlapped fields of a data
schema in `getOrInferFileFormatSchema`. Then, it respects column ordering in
`HadoopFsRelation#schema`.
## How was this patch tested?
Added tests in `ParquetPartitionDiscoverySuite` and change some tests in
`InsertIntoHiveTableSuite` and `MetastoreDataSourcesSuite`.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/maropu/spark SPARK-19005
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16410.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #16410
commit 9174e7c0686ddcd963a0232250dbcc50062d750b
Author: Takeshi YAMAMURO
Date: 2016-12-23T13:42:46Z
Keep column ordering when a schema is explicitly specified
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