mysql表的核心元数据

索引的

mysql> show indexes from recordsInRangeTest;
+--------------------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table              | Non_unique | Key_name     | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+--------------------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| recordsInRangeTest |          0 | PRIMARY      |            1 | id          | A         |       24290 |     NULL | NULL   |      | BTREE      |         |               |
| recordsInRangeTest |          1 | idx_name     |            1 | name        | A         |          12 |     NULL | NULL   | YES  | BTREE      |         |               |
| recordsInRangeTest |          1 | idx_age      |            1 | age         | A         |          12 |     NULL | NULL   | YES  | BTREE      |         |               |
| recordsInRangeTest |          1 | idx_age_name |            1 | name        | A         |          12 |     NULL | NULL   | YES  | BTREE      |         |               |
| recordsInRangeTest |          1 | idx_age_name |            2 | age         | A         |          22 |     NULL | NULL   | YES  | BTREE      |         |               |
+--------------------+------------+--------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
5 rows in set (0.00 sec)

 select * from innodb_index_stats where table_name='recordsInRangeTest';

+---------------+--------------------+--------------+---------------------+--------------+------------+-------------+-----------------------------------+
| database_name | table_name         | index_name   | last_update         | stat_name    | stat_value | sample_size | stat_description                  |
+---------------+--------------------+--------------+---------------------+--------------+------------+-------------+-----------------------------------+
| test          | recordsInRangeTest | PRIMARY      | 2018-07-17 05:02:50 | n_diff_pfx01 |      24290 |          20 | id                                |
| test          | recordsInRangeTest | PRIMARY      | 2018-07-17 05:02:50 | n_leaf_pages |         55 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | PRIMARY      | 2018-07-17 05:02:50 | size         |         97 |        NULL | Number of pages in the index      |
| test          | recordsInRangeTest | idx_age      | 2018-07-17 05:02:50 | n_diff_pfx01 |          6 |          29 | age                               |
| test          | recordsInRangeTest | idx_age      | 2018-07-17 05:02:50 | n_diff_pfx02 |      24576 |          29 | age,id                            |
| test          | recordsInRangeTest | idx_age      | 2018-07-17 05:02:50 | n_leaf_pages |         29 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | idx_age      | 2018-07-17 05:02:50 | size         |         30 |        NULL | Number of pages in the index      |
| test          | recordsInRangeTest | idx_age_name | 2018-07-17 05:02:50 | n_diff_pfx01 |          6 |          29 | name                              |
| test          | recordsInRangeTest | idx_age_name | 2018-07-17 05:02:50 | n_diff_pfx02 |         11 |          29 | name,age                          |
| test          | recordsInRangeTest | idx_age_name | 2018-07-17 05:02:50 | n_diff_pfx03 |      24576 |          29 | name,age,id                       |
| test          | recordsInRangeTest | idx_age_name | 2018-07-17 05:02:50 | n_leaf_pages |         29 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | idx_age_name | 2018-07-17 05:02:50 | size         |         30 |        NULL | Number of pages in the index      |
| test          | recordsInRangeTest | idx_name     | 2018-07-17 05:02:50 | n_diff_pfx01 |          6 |          24 | name                              |
| test          | recordsInRangeTest | idx_name     | 2018-07-17 05:02:50 | n_diff_pfx02 |      24576 |          24 | name,id                           |
| test          | recordsInRangeTest | idx_name     | 2018-07-17 05:02:50 | n_leaf_pages |         24 |        NULL | Number of leaf pages in the index |
| test          | recordsInRangeTest | idx_name     | 2018-07-17 05:02:50 | size         |         25 |        NULL | Number of pages in the index      |
+---------------+--------------------+--------------+---------------------+--------------+------------+-------------+-----------------------------------+

表本身的

+--------------------+--------+---------+------------+-------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-------------------+----------+----------------+---------+
| Name               | Engine | Version | Row_format | Rows  | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time         | Update_time | Check_time | Collation         | Checksum | Create_options | Comment |
+--------------------+--------+---------+------------+-------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-------------------+----------+----------------+---------+
| recordsInRangeTest | InnoDB |      10 | Compact    | 24290 |             65 |     1589248 |               0 |      1425408 |   4194304 |          28660 | 2018-06-09 09:29:26 | NULL        | NULL       | latin1_swedish_ci |     NULL |                |         |
+--------------------+--------+---------+------------+-------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-------------------+----------+----------------+---------+