http://mysql.rjweb.org/doc.php/index_cookbook_mysql
https://dba.stackexchange.com/questions/175300/existence-of-missing-index-in-mysql-does-it-exist
http://youdidwhatwithtsql.com/spotting-missing-indexes-mariadb-mysql/2036/
https://dev.mysql.com/blog-archive/mysql-explain-analyze/
https://github.com/rap2hpoutre/mysql-xplain-xplain
https://code.google.com/archive/p/php-sql-parser/wikis/ComplexExample.wiki