postgresql参数的设置

#服务配置文件postgresql.conf [postgres@fnddb data]$ ls -l postgresql.* -rw-------.

1 postgres postgres 88 Feb 4 22:20 postgresql.auto.conf -rw-------.

1 postgres postgres 21253 Feb 5 00:10 postgresql.conf postgresql.conf是默认的服务配置文件.因此大多数的修改参数都是在此文件中修改

postgresql.auto.conf是通过ALTER SYSTEM命令修改的参数

,这里的参数值生效会覆盖postgresql.conf文件中的值. 手动不要修改postgresql.auto.conf文件

 

 

postgresql参数的设置

 +

 

set shared_buffers='15GB';

 

1. [postgres@fnddb data]$ cat postgresql.auto.conf
2. # Do not edit this file manually!
3.   # It will be overwritten by the ALTER SYSTEM command.

#如何让刚修改的配置文件生效.
服务器进程收到SIGHUP信号,就会触发读取这两个配置文件.并且会把此信号传播到其他运行中的服务进程去.
pg自带的重载配置文件功能如下:

1.   [postgres@fnddb data]$ pg_ctl reload
2.   server signaled
3.   [postgres@fnddb data]$ psql
4.   psql ( 9.4.0)
5.   Type "help" for help.
6.   
7.   postgres= # select pg_reload_conf();
8.   pg_reload_conf
9.   ----------------
10.   t
11.  
    ( 1 row)

#通过sql来修改参数配置 不是所有的参数都可以在数据库运行的时候进行修改

###数据库级别参数设置###

1.   postgres= # create user u01 password 'postgres';
2.   CREATE ROLE
3.   postgres= # create database db01 owner u01;
4.   CREATE DATABASE
5.   postgres= # alter database postgres set enable_indexscan=off;
6.   ALTER DATABASE
7.   postgres= # \d pg_settings
8.   View "pg_catalog.pg_settings"
9.   Column | Type | Modifiers
10.   ------------+---------+-----------
11.   name | text |
12.   ......
13.   postgres= # \x
14.   Expanded display is on.
15.   postgres= # select * from pg_settings where name='enable_indexscan';
16.   -[ RECORD 1 ]----------------------------------------------
17.   name | enable_indexscan
18.   setting | off
19.   ......

换个用户

1.   postgres= # \c postgres u01
2.   You are now connected to database "postgres" as user "u01".
3.   postgres= # \x
4.   Expanded display is off.
5.   postgres=> select current_setting('enable_indexscan');
6.   current_setting
7.   -----------------
8.   off
9.   ( 1 row)

切换到db01数据库去

1.   postgres=> \c db01
2.   You are now connected to database "db01" as user "u01".
3.   db01=> select current_setting('enable_indexscan');
4.   current_setting
5.   -----------------
6.   on
7.   ( 1 row)

###用户级别的参数设置###

1.   db01=> \c
2.   You are now connected to database "db01" as user "u01".
3.   db01=> select current_setting('enable_indexscan');
4.   current_setting
5.   -----------------
6.   on
7.   ( 1 row)
8.   
9.   db01=> \c postgres
10.   You are now connected to database "postgres" as user "u01".
11.   postgres=> select current_setting('enable_indexscan');
12.   current_setting
13.   -----------------
14.   off
15.   ( 1 row)
16.   
17.   postgres=> alter role u01 set enable_indexscan=off;
18.   ALTER ROLE
19.   postgres=> \c db01
20.   You are now connected to database "db01" as user "u01".
21.   db01=> select current_setting('enable_indexscan');
22.   current_setting
23.   -----------------
24.   off
25.   ( 1 row)

###会话级别的参数设置###

1.   db01=> set enable_indexscan=off;
2.   SET
3.   db01=> select current_setting('enable_indexscan');
4.   current_setting
5.   -----------------
6.   off
7.   ( 1 row)
8.   
9.   db01=> \c
10.   You are now connected to database "db01" as user "u01".
11.   db01=> select current_setting('enable_indexscan');
12.   current_setting
13.   -----------------
14.   on
15.   ( 1 row)

###可以通过update pg_setting 来设置会话级参数

1.   db01=> update pg_settings set setting='on' where name = 'enable_indexscan';
2.   -[ RECORD 1 ]--
3.   set_config | on
4.   
5.   UPDATE 0
6.   db01=> select * from pg_settings where name='enable_indexscan';
7.   -[ RECORD 1 ]----------------------------------------------
8.   name | enable_indexscan
9.   setting | on
10.   ......

#参数还原

1.   db01=> set enable_indexscan to default;
2.   SET
3.   db01=> alter role u01 set enable_indexscan to default;
4.   ALTER ROLE
5.   db01=> alter database db01 set enable_indexscan to default;
6.   ALTER DATABASE

#结论:

1. ALTER DATABASE --影响范围是数据库级别
2. ALTER ROLE --影响范围是用户级别
3. SET --影响范围是会话级别
4. pg_settings,current_setting 查看的都是会话级别的

优先级: 会话级别 -> 用户级别 -> 数据库级别