Postgresql-快速启动，上手操作

1.安装

yum install -y postgresql-server postgresql postgresql-libs

2.初始化数据库

postgresql-setup initdb

3.服务停止、服务启动

[root@mysql8 ~]# systemctl stop postgresql.service

[root@mysql8 ~]# systemctl status postgresql.service

● postgresql.service - PostgreSQL database server

Loaded: loaded (/usr/lib/systemd/system/postgresql.service; disabled; vendor preset: disabled)

Active: inactive (dead)

Mar 06 23:22:57 mysql8 systemd[1]: Starting PostgreSQL database server...

Mar 06 23:22:57 mysql8 systemd[1]: postgresql.service: control process exited, code=exited status=1

Mar 06 23:22:57 mysql8 systemd[1]: Failed to start PostgreSQL database server.

Mar 06 23:22:57 mysql8 systemd[1]: Unit postgresql.service entered failed state.

Mar 06 23:22:57 mysql8 systemd[1]: postgresql.service failed.

Mar 06 23:26:37 mysql8 systemd[1]: Starting PostgreSQL database server...

Mar 06 23:26:38 mysql8 systemd[1]: Started PostgreSQL database server.

Mar 06 23:26:57 mysql8 systemd[1]: Stopping PostgreSQL database server...

Mar 06 23:26:58 mysql8 systemd[1]: Stopped PostgreSQL database server.

[root@mysql8 ~]# systemctl start postgresql.service

[root@mysql8 ~]# systemctl status postgresql.service

● postgresql.service - PostgreSQL database server

Loaded: loaded (/usr/lib/systemd/system/postgresql.service; disabled; vendor preset: disabled)

Active: active (running) since Fri 2020-03-06 23:26:38 CST; 3s ago

Process: 1695 ExecStart=/usr/bin/pg_ctl start -D ${PGDATA} -s -o -p ${PGPORT} -w -t 300 (code=exited, status=0/SUCCESS)

Process: 1690 ExecStartPre=/usr/bin/postgresql-check-db-dir ${PGDATA} (code=exited, status=0/SUCCESS)

Main PID: 1698 (postgres)

CGroup: /system.slice/postgresql.service

├─1698 /usr/bin/postgres -D /var/lib/pgsql/data -p 5432

├─1699 postgres: logger process

├─1701 postgres: checkpointer process

├─1702 postgres: writer process

├─1703 postgres: wal writer process

├─1704 postgres: autovacuum launcher process

└─1705 postgres: stats collector process

Mar 06 23:26:37 mysql8 systemd[1]: Starting PostgreSQL database server...

Mar 06 23:26:38 mysql8 systemd[1]: Started PostgreSQL database server.

4.登陆数据库

[root@mysql8 ~]# su - postgres

Last login: Fri Mar 6 23:32:22 CST 2020 on pts/0

-bash-4.2$ psql

psql (9.2.24)

Type "help" for help.

postgres=#

5.新手初试

postgres=# select current_database();

current_database

------------------

postgres

(1 row)

postgres=# select current_user;

current_user

--------------

postgres

(1 row)

postgres=# select inet_server_addr(),inet_server_port();

inet_server_addr | inet_server_port

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

(1 row)

postgres=# select version();

version

---------------------------------------------------------------------------------------------------------------

PostgreSQL 9.2.24 on x86_64-redhat-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-39), 64-bit

(1 row)

postgres=# \conninfo

You are connected to database "postgres" as user "postgres" via socket in "/var/run/postgresql" at port "5432".

帮助命令

postgres=# help

You are using psql, the command-line interface to PostgreSQL.

Type: \copyright for distribution terms

\h for help with SQL commands

\? for help with psql commands

\g or terminate with semicolon to execute query

\q to quit

postgres=# \h delete

Command: DELETE

Description: delete rows of a table

Syntax:

[ WITH [ RECURSIVE ] with_query [, ...] ]

DELETE FROM [ ONLY ] table_name [ * ] [ [ AS ] alias ]

[ USING using_list ]

[ WHERE condition | WHERE CURRENT OF cursor_name ]

[ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]

postgres=# \quit

6.DML操作，生成数据

#1.数据库创建

postgres=# create database test;

CREATE DATABASE

Time: 318.572 ms

postgres=# select * from pg_database;

rozenxid | dattablespace | datacl

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

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

template1 | 10 | 6 | en_US.UTF-8 | en_US.UTF-8 | t | t | -1 | 12921 |

1882 | 1663 | {=c/postgres,postgres=CTc/postgres}

template0 | 10 | 6 | en_US.UTF-8 | en_US.UTF-8 | t | f | -1 | 12921 |

1882 | 1663 | {=c/postgres,postgres=CTc/postgres}

postgres | 10 | 6 | en_US.UTF-8 | en_US.UTF-8 | f | t | -1 | 12921 |

1882 | 1663 |

test | 10 | 6 | en_US.UTF-8 | en_US.UTF-8 | f | t | -1 | 12921 |

1882 | 1663 |

(4 rows)

Time: 0.460 ms

#2.切换数据库

postgres=# \l

List of databases

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

(4 rows)

postgres=# \c test

You are now connected to database "test" as user "postgres".

#3.删除数据库

test=# drop database test;

ERROR: cannot drop the currently open database

Time: 0.744 ms

test=# \c postgres

You are now connected to database "postgres" as user "postgres".

postgres=# drop database test;

DROP DATABASE

Time: 108.722 ms

postgres=# \l

List of databases

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

(3 rows)

4.创建表

zhumh=# CREATE TABLE COMPANY(

zhumh(# ID INT PRIMARY KEY NOT NULL,

zhumh(# NAME TEXT NOT NULL,

zhumh(# AGE INT NOT NULL,

zhumh(# ADDRESS CHAR(50),

zhumh(# SALARY REAL

zhumh(# );

NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "company_pkey" for table "company"

CREATE TABLE

Time: 15.591 ms

zhumh=# CREATE TABLE DEPARTMENT(

zhumh(# ID INT PRIMARY KEY NOT NULL,

zhumh(# DEPT CHAR(50) NOT NULL,

zhumh(# EMP_ID INT NOT NULL

zhumh(# );

NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "department_pkey" for table "department"

CREATE TABLE

Time: 10.073 ms

zhumh=# \d

List of relations

Schema | Name | Type | Owner

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

public | company | table | postgres

public | department | table | postgres

(2 rows)

#查询表及表结构

zhumh=# \d company

Table "public.company"

Column | Type | Modifiers

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

id | integer | not null

name | text | not null

age | integer | not null

address | character(50) |

salary | real |

Indexes:

"company_pkey" PRIMARY KEY, btree (id)

5.删除表

zhumh=# drop table company,department;

DROP TABLE

Time: 12.968 ms

zhumh=# \d

No relations found.

6.表数据操作

zhumh=# CREATE TABLE COMPANY(

zhumh(# ID INT PRIMARY KEY NOT NULL,

zhumh(# NAME TEXT NOT NULL,

zhumh(# AGE INT NOT NULL,

zhumh(# ADDRESS CHAR(50),

zhumh(# SALARY REAL,

zhumh(# JOIN_DATE DATE

zhumh(# );

NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "company_pkey" for table "company"

CREATE TABLE

Time: 7.278 ms

zhumh=# INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY,JOIN_DATE) VALUES (1, 'Paul', 32, 'California', 20000.00,'2001-07-13');

INSERT 0 1

Time: 9.043 ms

zhumh=# INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,JOIN_DATE) VALUES (2, 'Allen', 25, 'Texas', '2007-12-13');

INSERT 0 1

Time: 0.813 ms

zhumh=# INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY,JOIN_DATE) VALUES (3, 'Teddy', 23, 'Norway', 20000.00, DEFAULT );

INSERT 0 1

Time: 2.300 ms

zhumh=# INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY,JOIN_DATE) VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00, '2007-12-13' ), (5, 'David', 27, 'Texas', 85000.00, '2007-12-13');

INSERT 0 2

Time: 0.730 ms

zhumh=# SELECT * FROM company;

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

1 | Paul | 32 | California | 20000 | 2001-07-13

2 | Allen | 25 | Texas | | 2007-12-13

3 | Teddy | 23 | Norway | 20000 |

4 | Mark | 25 | Rich-Mond | 65000 | 2007-12-13

5 | David | 27 | Texas | 85000 | 2007-12-13

(5 rows)

zhumh=# SELECT * FROM company where id=1;

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

1 | Paul | 32 | California | 20000 | 2001-07-13

(1 row)

zhumh=# UPDATE COMPANY SET SALARY = 15000 WHERE ID = 3;

UPDATE 1

Time: 2.168 ms

zhumh=# DELETE FROM COMPANY WHERE ID = 2;

DELETE 1

Time: 1.975 ms

zhumh=# SELECT * FROM COMPANY LIMIT 4;

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

1 | Paul | 32 | California | 20000 | 2001-07-13

4 | Mark | 25 | Rich-Mond | 65000 | 2007-12-13

5 | David | 27 | Texas | 85000 | 2007-12-13

3 | Teddy | 23 | Norway | 15000 |

(4 rows)

Time: 0.650 ms

基础操作参考信息：https://www.runoob.com/postgresql/postgresql-tutorial.html

7.了解你的数据库

1.服务程序运行时间

postgres=# select date_trunc('second',current_timestamp - pg_postmaster_start_time()) as uptime;

uptime

----------

00:20:06

(1 row)

2.查询数据库下有多少张表

postgres=# select count(*) from information_schema.tables where table_schema not in ('information_schema','pg_catalog');

count

-------

(1 row)

Time: 6.106 ms

postgres=# select count(*) from information_schema.tables where table_schema = 'information_schema';

count

-------

(1 row)

3.数据库占用空间

postgres=# select pg_database_size(current_database());

pg_database_size

------------------

6657144

(1 row)

Time: 0.955 ms

postgres=# select sum(pg_database_size(datname)) from pg_database;

sum

----------

26286724

(1 row)

4.表大小

postgres=# select pg_relation_size('pg_authid');

pg_relation_size

------------------

8192

(1 row)

Time: 0.515 ms

postgres=# select pg_total_relation_size('pg_authid');

pg_total_relation_size

------------------------

73728

(1 row)

Time: 0.448 ms

postgres=# \dt+ pg_authid

List of relations

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

(1 row)

5.最大表

postgres=# select table_name ,pg_relation_size(table_schema || '.' ||table_name ) as size

postgres-# from information_schema.tables

postgres-# where table_schema = 'pg_catalog'

postgres-# order by size desc

postgres-# limit 10;

table_name | size

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

pg_proc | 507904

pg_depend | 376832

pg_attribute | 344064

pg_description | 245760

pg_collation | 237568

pg_statistic | 122880

pg_operator | 114688

pg_rewrite | 98304

pg_class | 65536

pg_type | 65536

(10 rows)

6.表的行数

postgres=# select count(*) from pg_proc;

count

-------

2490

(1 row)

快速预估行数

postgres=# select (case when reltuples > 0 then

postgres(# pg_relation_size('pg_proc')*reltuples/(8192*relpages)

postgres(# else 0

postgres(# end)::bigint as estimated_row_count

postgres-# from pg_class

postgres-# where oid = 'pg_proc'::regclass;

estimated_row_count

---------------------

2490

(1 row)

Time: 0.711 ms

7.列出数据库扩展模块

postgres=# select * from pg_extension;

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

plpgsql | 10 | 11 | f | 1.0 | |

(1 row)

Postgresql-快速启动，上手操作

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