Revert "Refactor"

This reverts commit b68e7b1.
apache · Dec 10, 2018 · 93d8515 · 93d8515
1 parent b68e7b1
commit 93d8515
Showing 1 changed file with 13 additions and 6 deletions.
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveShim.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveShim.scala
@@ -53,12 +53,19 @@ private[hive] object HiveShim {
    * This function in hive-0.13 become private, but we have to do this to work around hive bug
    */
   private def appendReadColumnNames(conf: Configuration, cols: Seq[String]) {
-    val key = ColumnProjectionUtils.READ_COLUMN_NAMES_CONF_STR
-    val value = Option(conf.get(key, null))
-      .map(old => cols.+:(old))
-      .getOrElse(cols)
-      .mkString(",")
-    conf.set(key, value)
+    val old: String = conf.get(ColumnProjectionUtils.READ_COLUMN_NAMES_CONF_STR, "")
+    val result: StringBuilder = new StringBuilder(old)
+    var first: Boolean = old.isEmpty
+
+    for (col <- cols) {
+      if (first) {
+        first = false
+      } else {
+        result.append(',')
+      }
+      result.append(col)
+    }
+    conf.set(ColumnProjectionUtils.READ_COLUMN_NAMES_CONF_STR, result.toString)
   }
 
   /*