Sprinting is especially slow and since it's the fastest way to get around a map it's rough especially in terms of map creation. Although I will say that in general everything could use a bit of a bump. SELECT s.email AS email, s.city, s.Maybe since I've been playing a while, but it doesn't feel too awful to me. Or like this (turning the LEFT JOIN - check IS NULL into NOT EXISTS), which is sometimes faster: SELECT * SELECT s.email AS email, s.city, s.languageĬould be written like this (removing the two inner GROUP BY and turning UNION into UNION ALL ): SELECT * ( SELECT u.email AS email, u.city, u.language Add index on field email, on all 3 tables users, subscribers and mailchimp and run the query - and the EXPLAIN - again. I guess you have no indexes on the three tables. | NULL | UNION RESULT | | ALL | NULL | NULL | NULL | NULL | NULL | | | 3 | UNION | m | ALL | NULL | NULL | NULL | NULL | 11411 | Using where Not exists | | 3 | UNION | s | ALL | NULL | NULL | NULL | NULL | 2709 | Using temporary Using filesort | | 2 | DERIVED | m | ALL | NULL | NULL | NULL | NULL | 11411 | Using where Not exists | | 2 | DERIVED | u | ALL | NULL | NULL | NULL | NULL | 10482 | Using temporary Using filesort | | 1 | PRIMARY | | ALL | NULL | NULL | NULL | NULL | 23 | Using temporary Using filesort | | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | LEFT JOIN mailchimp AS m ON s.email = m.email WHERE m.email IS NULL GROUP BY s.email )ĪS sync GROUP BY sync.email ORDER BY sync.email ASC ĮXPLAIN for query +-+-+-+-+-+-+-+-+-+-+ UNION SELECT s.email AS email, s.city, s.language FROM subscribers AS s LEFT JOIN mailchimp AS m ON u.email = m.email WHERE m.email IS NULL GROUP BY u.email ( SELECT u.email AS email, u.city, u.language FROM users AS u Also including city and language with results.Īs you can see query_time is monster long and rows examined are just wtf combined 2 tables there should be only around 20k rows. Return all emails that are not in mailchimp table while doing it from 2 tables and return only DISTINCT values (users and subscribers emails might duplicate). I would like to ask some SQL experts how to correctly format and perform this SQL. Today noticed one SQL query that was extremely long in my mysql-slow.log
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