MySQL enforces indexes and disables an index

MySQL enforces indexes and disables an index

1, MySQL mandatory use index: Force index (index name or primary key PRI)

For example:

SELECT * FROM Table Force index (PRI) limit 2; (use primary key)

SELECT * FROM Table Force index (ZIDUAN1_INDEX) limit 2; (Enforce use of index "Ziduan1_index")

SELECT * FROM Table Force index (PRI,ZIDUAN1_INDEX) limit 2; (Forced use of index "PRI and Ziduan1_index")

2. MySQL prohibits an index: Ignore index (indexed name or primary key PRI)

For example:

SELECT * FROM table Ignore index (PRI) limit 2 (no primary key)

SELECT * FROM table Ignore index (ZIDUAN1_INDEX) limit 2; (Prohibit use of index "Ziduan1_index")

SELECT * FROM table Ignore index (PRI,ZIDUAN1_INDEX) limit 2; (Prohibit use of index "Pri,ziduan1_index")

MySQL enforces indexes and disables an index