In MySQL 'USE INDEX' is not working But 'FORCE Index' seems working fine

问题

EXPLAIN EXTENDED 

SELECT * FROM table_name

--  FORCE INDEX(dummy_date)

 USE INDEX(dummy_date)

where dummy_date 

between '2020-12-01' AND '2020-12-31'

AND name='something';

ALTER TABLE `table_name` ADD INDEX `dummy_date_index`(`dummy_date`)

When I execute this query then indexing is not working but if I use force index then its working with index. Please let me know the correct approach to use the index for millions of rows.

回答1:

Even better than MySQL not using indexes with WHERE IN clause? --

Use a better index and don't bother with USE or FORCE:

INDEX(name, dummy_date)

Anyway, if most of the table is in that month, then using INDEX(dummy_date) is less efficient than scanning the table.

来源：https://stackoverflow.com/questions/66007286/in-mysql-use-index-is-not-working-but-force-index-seems-working-fine