MySQL慢查询：如何优化以下查询？

Question

Following is the query that i am using:

SELECT *
FROM (
    SELECT 
        (
            CASE WHEN product_name like '%word1%' THEN 1 ELSE 0 END +
            CASE WHEN product_name like '%word2%' THEN 1 ELSE 0 END +
            CASE WHEN product_name like '%word3%' THEN 1 ELSE 0 END
        ) AS numMatches
    FROM products as p 
   ) as derived
WHERE numMatches > 0
ORDER BY numMatches DESC
LIMIT 30,10

I added an index (BTREE) on product_name, there are 3 million records in the column, the query is executing in 3-5 seconds.

Explain says 'Using where; Using filesort' so i can figure out its not using the index.

Answer 1

No, it's not using the index.

For that, you would have to compare with 'word1%', 'word2%', etc.. but doesn't work when you use the joker at the beginning.

But, If your mysql version is relatively modern you can use fulltext indexes, which would serve for your query.

https://dev.mysql.com/doc/refman/5.6/en/innodb-fulltext-index.html