innodb_index_stats

mysql> select * from mysql.innodb_index_stats WHERE        database_name='test' and table_name='recordsInRangeTest';
+---------------+--------------------+--------------+---------------------+--------------+------------+-------------+-----------------------------------+
| database_name | table_name         | index_name   | last_update         | stat_name    | stat_value | sample_size | stat_description                  |
+---------------+--------------------+--------------+---------------------+--------------+------------+-------------+-----------------------------------+
| test          | recordsInRangeTest | PRIMARY      | 2018-07-14 04:27:29 | n_diff_pfx01 |      24290 |          20 | id                                |
| test          | recordsInRangeTest | PRIMARY      | 2018-07-14 04:27:29 | n_leaf_pages |         55 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | PRIMARY      | 2018-07-14 04:27:29 | size         |         97 |        NULL | Number of pages in the index      |
| test          | recordsInRangeTest | idx_age      | 2018-07-14 04:27:29 | n_diff_pfx01 |          6 |          29 | age                               |
| test          | recordsInRangeTest | idx_age      | 2018-07-14 04:27:29 | n_diff_pfx02 |      24576 |          29 | age,id                            |
| test          | recordsInRangeTest | idx_age      | 2018-07-14 04:27:29 | n_leaf_pages |         29 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | idx_age      | 2018-07-14 04:27:29 | size         |         30 |        NULL | Number of pages in the index      |
| test          | recordsInRangeTest | idx_age_name | 2018-07-14 04:27:29 | n_diff_pfx01 |          6 |          30 | name                              |
| test          | recordsInRangeTest | idx_age_name | 2018-07-14 04:27:29 | n_diff_pfx02 |         11 |          30 | name,age                          |
| test          | recordsInRangeTest | idx_age_name | 2018-07-14 04:27:29 | n_diff_pfx03 |      24576 |          30 | name,age,id                       |
| test          | recordsInRangeTest | idx_age_name | 2018-07-14 04:27:29 | n_leaf_pages |         30 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | idx_age_name | 2018-07-14 04:27:29 | size         |         31 |        NULL | Number of pages in the index      |
| test          | recordsInRangeTest | idx_name     | 2018-07-14 04:27:29 | n_diff_pfx01 |          6 |          25 | name                              |
| test          | recordsInRangeTest | idx_name     | 2018-07-14 04:27:29 | n_diff_pfx02 |      24576 |          25 | name,id                           |
| test          | recordsInRangeTest | idx_name     | 2018-07-14 04:27:29 | n_leaf_pages |         25 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | idx_name     | 2018-07-14 04:27:29 | size         |         26 |        NULL | Number of pages in the index      |
+---------------+--------------------+--------------+---------------------+--------------+------------+-------------+-----------------------------------+