Can you explain the logical architecture of MySQL?

The top layer contains the services most network-based client/server tools or servers need such as connection handling, authentication, security, and so forth. The second layer contains much of MySQL’s brains. This has the code for query parsing, analysis, optimization, caching, and all the built-in functions.

mysql> explain select * from books;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key  | key_len | ref  | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
|  1 | SIMPLE      | books | NULL       | ALL  | NULL          | NULL | NULL    | NULL |    3 |   100.00 | NULL  |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
1 row in set, 1 warning (0.00 sec)