显示和设置该连接当前运行参数

• 显示当前连接的运行参数。

    postgres=# SELECT CURRENT_USER; 
    current_user 
   --------------
    tbase
   (1 row)
  
   postgres=# show search_path ;
    search_path   
   ----------------
    "$user",public
   (1 row)
  
   postgres=# show work_mem ;
    work_mem 
   ----------
    4MB
   (1 row)

• 设置当前连接的运行参数。

   postgres=# set search_path ="$user",public,pg_catalog;
   SET
   postgres=# set work_mem = '8MB';
   SET

• 打开和关闭显示每个sql语句执行的时间。

   postgres=# \timing on
   Timing is on.
   postgres=# select count(1) from tbase;
    count 
   -------
    10000
   (1 row)
  
   Time: 5.139 ms
   postgres=# \timing off
   Timing is off.
   postgres=# select count(1) from tbase;
    count 
   -------
    10000
   (1 row)

• 打开和关闭显示每个快捷操作符实际运行的sql语句。

   postgres=# \set ECHO_HIDDEN on
  
   postgres=# \dt
  
   ********* QUERY **********
  
   SELECT n.nspname as "Schema",
  
  

c.relname as "Name",

CASE c.relkind WHEN 'r' THEN 'table' WHEN 'v' THEN 'view' WHEN 'm' THEN 'materialized view' WHEN 'i' THEN 'index' WHEN 'S' THEN 'sequence' WHEN 's' THEN 'special' WHEN 'f' THEN 'foreign table' END as "Type",

pg_catalog.pg_get_userbyid(c.relowner) as "Owner"

FROM pg_catalog.pg_class c

LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace

WHERE c.relkind IN ('r','')

AND n.nspname <> 'pg_catalog'

AND n.nspname <> 'information_schema'

AND n.nspname !~ '^pg_toast'

AND pg_catalog.pg_table_is_visible(c.oid)

ORDER BY 1,2;

List of relations

Schema | Name | Type | Owner

--------+--------------+-------+-------

public | t_time_range | table | tbase

public | tbase | table | tbase

(2 rows)

postgres=# \set ECHO_HIDDEN off

postgres=# \dt

List of relations

Schema | Name | Type | Owner

--------+--------------+-------+-------

public | t_time_range | table | tbase

public | tbase | table | tbase

(2 rows)

  - 配置输出结果为HTML格式

      ``` cpp

      postgres=# \pset format html

      Output format is html.

      postgres=# \d tbase            

      <table border="1">


      <caption>Table "public.tbase"</caption>


      <tr>


      <th align="center">Column</th>


      <th align="center">Type</th>


      <th align="center">Modifiers</th>


      </tr>


      <tr valign="top">


      <td align="left">id</td>


      <td align="left">integer</td>


      <td align="left">


      </tr>


      <tr valign="top">


      <td align="left">mc</td>


      <td align="left">text</td>


      <td align="left">


      </tr>

      </table>


      恢复为对齐模式

      postgres=# \pset format aligned

      Output format is aligned.

      postgres=# \d tbase            


      Table "public.tbase"


      Column |  Type   | Modifiers 

      --------+---------+-----------


      id     | integer | 


      mc     | text    | 


      ```
  - 配置行列显示格式

      ``` cpp

      postgres=# \x on
      Expanded display is on.
      postgres=# select * from tbase where id=1;
      -[ RECORD 1 ]
      id | 1
      mc | 1
      -[ RECORD 2 ]
      id | 1
      mc | 2
      -[ RECORD 3 ]
      id | 1
      mc | 2

      postgres=# \x off
      Expanded display is off.
      postgres=# select * from tbase where id=1;
       id | mc 
      ----+----
        1 | 1
        1 | 2
        1 | 2
      (3 rows)


      ```
  - 显示和配置客户端编码

      ``` cpp
      postgres=# \encoding 
      UTF8
      #配置客户端编码为SQL_ASCII
      postgres=# \encoding sql_ascii
      postgres=# \encoding 
      SQL_ASCII
      ```