参见MySQL文档
FORCE INDEX。
JOIN survey_customer_similarity AS scs FORCE INDEX (CONSUMER_ID_1,CONSUMER_ID_2)ONcr.CONSUMER_ID=scs.CONSUMER_ID_2 AND cal.SENDER_CONSUMER_ID=scs.CONSUMER_ID_1 OR cr.CONSUMER_ID=scs.CONSUMER_ID_1 AND cal.SENDER_CONSUMER_ID=scs.CONSUMER_ID_2
正如TheScrumMeister在下面指出的那样，它是否可以同时实际使用两个索引取决于您的数据。
这是一个示例，您需要强制该表出现两次以控制查询的执行和交集。
使用它来创建一个包含100K条记录的表，其中约1K行与过滤条件匹配，
i in (2,3)而1K行与
j in (2,3)以下条件匹配：
drop table if exists t1;create table t1 (id int auto_increment primary key, i int, j int);create index ix_t1_on_i on t1(i);create index ix_t1_on_j on t1(j);insert into t1 (i,j) values (2,2),(2,3),(4,5),(6,6),(2,6),(2,7),(3,2);insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i*2, j*2+i from t1;insert into t1 (i,j) select i, j from t1;insert into t1 (i,j) select i, j from t1;insert into t1 (i,j) select 2, j from t1 where not j in (2,3) limit 1000;insert into t1 (i,j) select i, 3 from t1 where not i in (2,3) limit 1000;
进行时：
select t.* from t1 as t where t.i=2 and t.j=3 or t.i=3 and t.j=2
您将获得8场匹配的比赛：
+-------+------+------+| id | i | j |+-------+------+------+| 7 | 3 | 2 || 28679 | 3 | 2 || 57351 | 3 | 2 || 86023 | 3 | 2 || 2 | 2 | 3 || 28674 | 2 | 3 || 57346 | 2 | 3 || 86018 | 2 | 3 |+-------+------+------+
EXPLAIN在上面的查询中使用以获取：
id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra1 | SIMPLE | t | range | ix_t1_on_i,ix_t1_on_j | ix_t1_on_j | 5 | NULL | 1012 | Using where
即使我们
FORCE INDEX在两个索引上添加查询，
EXPLAIN也将返回 完全相同的内容 。
要使其跨两个索引收集，然后相交，请使用以下命令：
select t.* from t1 as a force index(ix_t1_on_i)join t1 as b force index(ix_t1_on_j) on a.id=b.idwhere a.i=2 and b.j=3 or a.i=3 and b.j=2
使用该查询
explain可获取：
id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra1 | SIMPLE | a | range | ix_t1_on_i | ix_t1_on_i | 5 | NULL | 1019 | Using where1 | SIMPLE | b | range | ix_t1_on_j | ix_t1_on_j | 5 | NULL | 1012 | Using where; Using index
这证明正在使用索引。但这可能会更快，也可能不会更快，这取决于许多其他因素。
