CREATE TABLE `willtest10` (

  `thedate` int(11) NOT NULL,

  `dtEventTime` varchar(32) NOT NULL,

  `dtEventTimeStamp` bigint(20) NOT NULL,

  `metrics` text,

  `data_cnt` bigint(20) DEFAULT NULL,

  KEY `ind_metrics` (`metrics`(30),`dtEventTimeStamp`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='shard_key "dtEventTimeStamp"'

/*!50100 PARTITION BY RANGE (thedate)

(PARTITION p20190904 VALUES LESS THAN (20190904) ENGINE = InnoDB,

 PARTITION p20190925 VALUES LESS THAN (20190925) ENGINE = InnoDB) */ ;

INSERT INTO `willtest10` VALUES (20190903,'2019-09-03 23:58:00',1567526280000,'com.parties.metrics.QueueMetrics.1100.playersEnteredQueue',1),(20190922,'2019-09-22 02:57:00',1569092220000,'com.parties.metrics.QueueMetrics.1100.playersEnteredQueue',1),(20190923,'2019-09-23 02:44:00',1569177840000,'com.parties.metrics.QueueMetrics.1090.playersEnteredQueue',1),(20190923,'2019-09-23 02:44:00',1569177840000,'com.parties.metrics.QueueMetrics.840.playersEnteredQueue',1);

mysql> select * from willtest10 order by dtEventTimeStamp desc;

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

| thedate  | dtEventTime         | dtEventTimeStamp | metrics                                                   | data_cnt |

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

| 20190923 | 2019-09-23 02:44:00 |    1569177840000 | com.parties.metrics.QueueMetrics.1090.playersEnteredQueue |        1 |

| 20190923 | 2019-09-23 02:44:00 |    1569177840000 | com.parties.metrics.QueueMetrics.840.playersEnteredQueue  |        1 |

| 20190922 | 2019-09-22 02:57:00 |    1569092220000 | com.parties.metrics.QueueMetrics.1100.playersEnteredQueue |        1 |

| 20190903 | 2019-09-03 23:58:00 |    1567526280000 | com.parties.metrics.QueueMetrics.1100.playersEnteredQueue |        1 |

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

4 rows in set (0.00 sec)

mysql> select * FROM willtest10 force index(ind_metrics) WHERE  metrics = 'com.parties.metrics.QueueMetrics.1100.playersEnteredQueue'  ORDER BY dtEven

tTimeStamp  desc limit 1 ;

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

| thedate  | dtEventTime         | dtEventTimeStamp | metrics                                                   | data_cnt |

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

| 20190903 | 2019-09-03 23:58:00 |    1567526280000 | com.parties.metrics.QueueMetrics.1100.playersEnteredQueue |        1 |

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

1 row in set (0.00 sec)

mysql> select * FROM willtest10 force index(ind_metrics) WHERE  metrics = 'com.parties.metrics.QueueMetrics.1100.playersEnteredQueue'  ORDER BY dtEven

tTimeStamp  desc  ;

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

| thedate  | dtEventTime         | dtEventTimeStamp | metrics                                                   | data_cnt |

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

| 20190903 | 2019-09-03 23:58:00 |    1567526280000 | com.parties.metrics.QueueMetrics.1100.playersEnteredQueue |        1 |

| 20190922 | 2019-09-22 02:57:00 |    1569092220000 | com.parties.metrics.QueueMetrics.1100.playersEnteredQueue |        1 |

+----------+---------------------+------------------+-----------------------------------------------------------+----------+

2 rows in set (0.00 sec)

diff --git a/sql/sql_select.cc b/sql/sql_select.cc

index 60c367e20c0..e4cdc08138d 100644

--- a/sql/sql_select.cc

+++ b/sql/sql_select.cc

@@ -21942,6 +21942,28 @@ void compute_part_of_sort_key_for_equals(JOIN *join, TABLE *table,

 }

+bool is_perfix_index(TABLE* table, int key, uint key_parts )

+{

+  if (!table || !table->key_info)

+  {

+    return false;

+  }

+  KEY_PART_INFO* key_part = table->key_info[key].key_part;

+  KEY* key_info = table->key_info + key;

+

+  for (uint i = 0; i < key_parts; i++, key_part++)

+  {

+    if (key_part->field &&

+      (key_part->length !=

+        table->field[key_part->fieldnr - 1]->key_length() &&

+        !(key_info->flags & (HA_FULLTEXT | HA_SPATIAL))))

+    {

+      return true;

+    }

+  }

+  return false;

+}

+

 /**

   Test if we can skip the ORDER BY by using an index.

@@ -22065,6 +22087,12 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,

     }

   }

+  if ( is_perfix_index(table, ref_key, ref_key_parts) &&

+    table && table->part_info && order)

+  {

+    DBUG_RETURN(0);

+  }

+

   if (ref_key >= 0 && ref_key != MAX_KEY)

   {

     /* Current access method uses index ref_key with ref_key_parts parts */