是的，没错

我在 rails 5 中发现，any? 和 empty? 都是 select 1

User.where(effective: true).any?
  User Exists (0.9ms)  SELECT  1 AS one FROM "users" WHERE "users"."deleted_at" IS NULL AND "users"."effective" = $1 LIMIT $2  [["effective", true], ["LIMIT", 1]]
 => true 
2.5.1 :005 > User.where(effective: true).empty?
  User Exists (0.8ms)  SELECT  1 AS one FROM "users" WHERE "users"."deleted_at" IS NULL AND "users"."effective" = $1 LIMIT $2  [["effective", true], ["LIMIT", 1]]
 => false 

数据量大的时候，select count(*) 也会慢的吧，而 select 1 会很快

推荐用这个 https://freessl.cn/ 一个提供免费 HTTPS 证书申请的网站，（Let's Encrypt 与 TrustAsia）我刚试了， https://lumao.vicw.com/ 这是我搞的撸猫网，证书有效期 1 年，可以续订，比自己搞简单多了