EXPLAIN PARTITIONS select RunDate from TTprices where RunDate>='20040204' group by RunDate limit 5;
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
| id | select_type | table    | partitions                 | type   | possible_keys | key         | key_len | ref    | rows   | Extra                                 |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
|  1 | SIMPLE      | TTprices | p0,p1,p2,p3,p4,p5,p6,p7,p8 | range  | Rundate_key   | Rundate_key | 10      | [NULL] |      8 | Using where; Using index for group-by |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+


EXPLAIN PARTITIONS select RunDate from TTprices where RunDate>='20040204' order by RunDate limit 5;
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+-----------+--------------------------+
| id | select_type | table    | partitions                 | type   | possible_keys | key         | key_len | ref    | rows      | Extra                    |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+-----------+--------------------------+
|  1 | SIMPLE      | TTprices | p0,p1,p2,p3,p4,p5,p6,p7,p8 | range  | Rundate_key   | Rundate_key | 10      | [NULL] | 108467844 | Using where; Using index |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+-----------+--------------------------+


EXPLAIN PARTITIONS select distinct RunDate from TTprices where RunDate>='20040204' order by RunDate
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
| id | select_type | table    | partitions                 | type   | possible_keys | key         | key_len | ref    | rows   | Extra                                 |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
|  1 | SIMPLE      | TTprices | p0,p1,p2,p3,p4,p5,p6,p7,p8 | range  | Rundate_key   | Rundate_key | 10      | [NULL] |      8 | Using where; Using index for group-by |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+


EXPLAIN PARTITIONS select RunDate from TTprices where RunDate>='20070204' group by RunDate limit 5;
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
| id | select_type | table    | partitions                 | type   | possible_keys | key         | key_len | ref    | rows   | Extra                                 |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
|  1 | SIMPLE      | TTprices | p0,p1,p2,p3,p4,p5,p6,p7,p8 | range  | Rundate_key   | Rundate_key | 10      | [NULL] |      4 | Using where; Using index for group-by |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+


EXPLAIN PARTITIONS select RunDate from TTprices where RunDate>='20070204' order by RunDate limit 5;
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+----------+--------------------------+
| id | select_type | table    | partitions                 | type   | possible_keys | key         | key_len | ref    | rows     | Extra                    |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+----------+--------------------------+
|  1 | SIMPLE      | TTprices | p0,p1,p2,p3,p4,p5,p6,p7,p8 | range  | Rundate_key   | Rundate_key | 10      | [NULL] | 47222190 | Using where; Using index |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+----------+--------------------------+


EXPLAIN PARTITIONS select distinct RunDate from TTprices where RunDate>='20070204' order by RunDate limit 5;
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
| id | select_type | table    | partitions                 | type   | possible_keys | key         | key_len | ref    | rows   | Extra                                 |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+
|  1 | SIMPLE      | TTprices | p0,p1,p2,p3,p4,p5,p6,p7,p8 | range  | Rundate_key   | Rundate_key | 10      | [NULL] |      4 | Using where; Using index for group-by |
+----+-------------+----------+----------------------------+--------+---------------+-------------+---------+--------+--------+---------------------------------------+