更多的探索表明以下内容可以解决问题:

A bit more exploration shows the following will do the job:

new Sequelize('mydb', undefined, undefined, {
     host: '/var/run/postgresql',
     dialect: 'postgres'
   });

实际连接由包 'pg' 处理，这在 中有记录问题.

The actual connection is handled by the package 'pg' and this was documented in an issue.

注意，我已经测试过它可以与 pg@6.4.1 和 sequelize@4.4.2 一起使用.

Note, I have tested this to work with pg@6.4.1 and sequelize@4.4.2.