[SPARK-16034][SQL] Checks the partition columns when calling dataFrame.write.mode("append").saveAsTable

sql/core/src/main/scala/org/apache/spark/sql/execution/command/createDataSourceTables.scala

@@ -242,8 +242,13 @@ case class CreateDataSourceTableAsSelectCommand(
       bucketSpec = bucketSpec,
       options = optionsWithPath)
 
-    val result = dataSource.write(mode, df)
-
+    val result = try {
+      dataSource.write(mode, df)
+    } catch {
+      case ex: AnalysisException =>
+        logError(s"Failed to write to table ${tableIdent.identifier} in $mode mode", ex)
+        throw ex
+    }
     if (createMetastoreTable) {
       // We will use the schema of resolved.relation as the schema of the table (instead of
       // the schema of df). It is important since the nullability may be changed by the relation

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DataSource.scala

@@ -435,26 +435,25 @@ case class DataSource(
         // If we are appending to a table that already exists, make sure the partitioning matches
         // up.  If we fail to load the table for whatever reason, ignore the check.
         if (mode == SaveMode.Append) {
-          val existingPartitionColumnSet = try {
-            Some(
-              resolveRelation()
-                .asInstanceOf[HadoopFsRelation]
-                .location
-                .partitionSpec()
-                .partitionColumns
-                .fieldNames
-                .toSet)
-          } catch {
-            case e: Exception =>
-              None
-          }
-
-          existingPartitionColumnSet.foreach { ex =>
-            if (ex.map(_.toLowerCase) != partitionColumns.map(_.toLowerCase()).toSet) {
-              throw new AnalysisException(
-                s"Requested partitioning does not equal existing partitioning: " +
-                s"$ex != ${partitionColumns.toSet}.")
-            }
+          val existingColumns = Try {
+            resolveRelation()
+              .asInstanceOf[HadoopFsRelation]
+              .location
+              .partitionSpec()
+              .partitionColumns
+              .fieldNames
+              .toSeq
+          }.getOrElse(Seq.empty[String])
+          val sameColumns =
+            existingColumns.map(_.toLowerCase) == partitionColumns.map(_.toLowerCase)
+          if (existingColumns.size > 0 && !sameColumns) {
+            throw new AnalysisException(
+              s"""Requested partitioning does not match existing partitioning.
+                 |Existing partitioning columns:
+                 |  ${existingColumns.mkString(", ")}
+                 |Requested partitioning columns:
+                 |  ${partitionColumns.mkString(", ")}
+                 |""".stripMargin)
           }
         }
 

sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala

@@ -1317,4 +1317,28 @@ class DDLSuite extends QueryTest with SharedSQLContext with BeforeAndAfterEach {
     assertUnsupported("TRUNCATE TABLE my_tab PARTITION (age=10)")
   }
 
+  test("SPARK-16034 Partition columns should match when appending to existing data source tables") {
+    import testImplicits._
+    val df = Seq((1, 2, 3)).toDF("a", "b", "c")
+    withTable("partitionedTable") {
+      df.write.mode("overwrite").partitionBy("a", "b").saveAsTable("partitionedTable")
+      // Misses some partition columns
+      intercept[AnalysisException] {
+        df.write.mode("append").partitionBy("a").saveAsTable("partitionedTable")
+      }
+      // Wrong order
+      intercept[AnalysisException] {
+        df.write.mode("append").partitionBy("b", "a").saveAsTable("partitionedTable")
+      }
+      // Partition columns not specified
+      intercept[AnalysisException] {
+        df.write.mode("append").saveAsTable("partitionedTable")
+      }
+      assert(sql("select * from partitionedTable").collect().size == 1)
+      // Inserts new data successfully when partition columns are correctly specified in
+      // partitionBy(...).
+      df.write.mode("append").partitionBy("a", "b").saveAsTable("partitionedTable")
+      assert(sql("select * from partitionedTable").collect().size == 2)
+    }
+  }
 }