diff --git a/docs/sql-programming-guide.md b/docs/sql-programming-guide.md
index 332618edf0c5..03500867df70 100644
--- a/docs/sql-programming-guide.md
+++ b/docs/sql-programming-guide.md
@@ -1371,7 +1371,10 @@ the Data Sources API.  The following options are supported:
     <td>
       These options must all be specified if any of them is specified.  They describe how to
       partition the table when reading in parallel from multiple workers.
-      <code>partitionColumn</code> must be a numeric column from the table in question.
+      <code>partitionColumn</code> must be a numeric column from the table in question. Notice
+      that <code>lowerBound</code> and <code>upperBound</code> are just used to decide the
+      partition stride, not for filtering the rows in table. So all rows in the table will be
+      partitioned and returned.
     </td>
   </tr>
 </table>
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
index c25ef58e6f62..b237fe684cdc 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
@@ -873,8 +873,8 @@ class SQLContext(@transient val sparkContext: SparkContext)
    * passed to this function.
    *
    * @param columnName the name of a column of integral type that will be used for partitioning.
-   * @param lowerBound the minimum value of `columnName` to retrieve
-   * @param upperBound the maximum value of `columnName` to retrieve
+   * @param lowerBound the minimum value of `columnName` used to decide partition stride
+   * @param upperBound the maximum value of `columnName` used to decide partition stride
    * @param numPartitions the number of partitions.  the range `minValue`-`maxValue` will be split
    *                      evenly into this many partitions
    *
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JDBCRelation.scala b/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JDBCRelation.scala
index 4fa84dc076f7..1c113b34a1ae 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JDBCRelation.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JDBCRelation.scala
@@ -50,9 +50,11 @@ private[sql] object JDBCRelation {
    * Given a partitioning schematic (a column of integral type, a number of
    * partitions, and upper and lower bounds on the column's value), generate
    * WHERE clauses for each partition so that each row in the table appears
-   * exactly once.  The parameters minValue and maxValue are advisory in that
+   * exactly once. The parameters minValue and maxValue are advisory in that
    * incorrect values may cause the partitioning to be poor, but no data
-   * will fail to be represented.
+   * will fail to be represented. Note: the upper and lower bounds are just
+   * used to decide partition stride, not for filtering. So all the rows in
+   * table will be partitioned.
    */
   def columnPartition(partitioning: JDBCPartitioningInfo): Array[Partition] = {
     if (partitioning == null) return Array[Partition](JDBCPartition(null, 0))