postgresql - Difference between set, \set and \pset in psql

Question

I get a little confused some times when working with psql between when to use a set vs. \set vs. \pset. I think that:

• set is for session variables on my connection to the db. For example SET ROLE dba;
• \set is for local variables for this psql session. For example \set time 'select current_timestamp'
• \pset is for psql settings for this psql session. For example '\pset border 2'

But, I've never found what I thought was a good explanation of each. Are my assumptions above correct?

I'm using PostgreSQL 9.4

Answer 1

基本正确。重要的区别在于它SET是一个 SQL 命令，而另外两个是 psql 元命令 - 由前缀表示\。

• SET是用于更改运行时参数的 SQL 命令。它在服务器上执行，与 psql 本身无关。

• \set是一个 psql 元命令，并且根据文档：

将 psql 变量名称设置为值 [...]

注意：此命令与 SQL 命令无关SET。

• \pset是另一个 psql 元命令。根据文档：

此命令设置影响查询结果表输出的选项