Postgresql学习笔记系列参考来源：
PostgreSQL 9.5.4 Documentation

对应章节：
Preface: Conventions

brackets ([ and ]) indicate optional parts.
中括号[ ] 代表可选项

Braces ({ and }) and vertical lines (|) indicate that you must choose one alternative.
花括号{ } 和竖线| 表示必须选择一个

Dots (…) mean that the preceding element can be repeated.
… 表示后面的元素可以重复

sql命令提示符=>
shell命令提示符 $

administrator和user An administrator is generally a person who is in charge of installing and running the server. A user could be anyone who is using,or wants to use,any part of the Postgresql system. These terms should not be interpreted too narrowly; this book does not have fixed presumptions about system administration procedures.