小编Sat*_*ato的帖子

例如，这是一个示例表

id int PK,
pid int,
cid int,
deleted int,
createdAt timestamp,
UNIQUE KEY pid_cid(pid, cid)

使用的 WHERE 子句是

where pid=$pid and cid=$cid [and deleted = 1];
where pid=$pid [and deleted = 1];
where cid=$pid [and deleted = 1];

既然我已经索引了UNIQUE KEY pid_cid(pid, cid)，我应该分别索引 pid 和 cid 吗？

还是选择 aindex pid比选择a快UNIQUE KEY pid_cid(pid, cid)？