史上最全：PostgreSQL DBA常用SQL查询语句（建议收藏学习）

DB=# help --总的帮助
DB=# \h --SQL commands级的帮助
DB=# \? --psql commands级的帮助

DB=# \x
Expanded display is on.

find / -name initdb

find / -name postgresql.conf

cat $PGDATA/PG_VERSION

psql --version

DB=# show server_version;

DB=# select version();

pg_ctl status

psql –l --查看5432端口下面有多少个DB

psql –p XX –l --查看XX端口下面有多少个DB

DB=# \l

DB=# select * from pg_database;

createdb database_name

DB=# \h create database --创建数据库的帮助命令

DB=# create database database_name

psql –d dbname

DB=# \c dbname

DB=# \c

DB=# select current_database();

DB=# show data_directory;

cat $PGDATA/postgresql.conf |grep data_directory

cat /etc/init.d/postgresql|grep PGDATA=

lsof |grep 得出第二列的PID号再ps –ef|grep PID

select * from pg_tablespace;

select * from pg_language;

select * from information_schema.schemata;

SELECT nspname FROM pg_namespace;

\dnS

DB=# \dt --只能查看到当前数据库下public的表名

DB=# SELECT tablename FROM pg_tables WHERE tablename NOT LIKE 'pg%' AND tablename NOT LIKE 'sql_%' ORDER BY tablename;

DB=# SELECT * FROM information_schema.tables WHERE table_name='ff_v3_ff_basic_af';

DB=# \d tablename

DB=# select * from information_schema.columns where table_schema='public' and table_name='XX';

DB=# \di

DB=# select * from pg_index;

DB=# \dv

DB=# select * from pg_views where schemaname = 'public';

DB=# select * from information_schema.views where table_schema = 'public';

DB=# select * from information_schema.triggers;

DB=# select * from information_schema.sequences where sequence_schema = 'public';

DB=# select * from pg_constraint where contype = 'p'

DB=# select a.relname as table_name,b.conname as constraint_name,b.contype as constraint_type from pg_class a,pg_constraint b where a.oid = b.conrelid and a.relname = 'cc';

SELECT pg_size_pretty(pg_database_size('XX')) As fulldbsize;

select pg_database.datname, pg_size_pretty (pg_database_size(pg_database.datname)) AS size from pg_database;

select datname,(pg_stat_file(format('%s/%s/PG_VERSION',case when spcname='pg_default' then 'base' else 'pg_tblspc/'||t2.oid||'/PG_11_201804061/' end, t1.oid))).* from pg_database t1,pg_tablespace t2 where t1.dattablespace=t2.oid;

select relname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_tables where schemaname='public' order by pg_relation_size(relid) desc;

select indexrelname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_indexes where schemaname='public' order by pg_relation_size(relid) desc;

DB=# show config_file;
DB=# show hba_file;
DB=# show ident_file;

DB=# show all;

select * from pg_file_settings

DB=# show work_mem

DB=# alter system set work_mem='8MB'

--使用alter system命令将修改postgresql.auto.conf文件，而不是postgresql.conf，这样可以很好的保护postgresql.conf文件，加入你使用很多alter system命令后搞的一团糟，那么你只需要删除postgresql.auto.conf，再执行pg_ctl reload加载postgresql.conf文件即可实现参数的重新加载。

DB=# show archive_mode;

show logging_collector;--启动日志收集
show log_directory;--日志输出路径
show log_filename;--日志文件名
show log_truncate_on_rotation;--当生成新的文件时如果文件名已存在，是否覆盖同名旧文件名
show log_statement;--设置日志记录内容
show log_min_duration_statement;--运行XX毫秒的语句会被记录到日志中，-1表示禁用这个功能，0表示记录所有语句，类似mysql的慢查询配置

存放在data_directory/pg_wal目录

DB=# \c
DB=# select current_user;

DB=# select * from pg_user;
DB=# select * from pg_shadow;

DB=# \du
DB=# select * from pg_roles;

select * from information_schema.table_privileges where grantee='XX';

create user XXX SUPERUSER PASSWORD '123456'

create role "user1" superuser;--pg_roles有user1，pg_user和pg_shadow没有user1

alter role "user1" login;--pg_user和pg_shadow也有user1了

DB=# \h grant

GRANT ALL PRIVILEGES ON schema schemaname TO dbuser;

grant ALL PRIVILEGES on all tables in schema fds to dbuser;

GRANT ALL ON tablename TO user;

GRANT ALL PRIVILEGES ON DATABASE dbname TO dbuser;

grant select on all tables in schema public to dbuser;--给用户读取public这个schema下的所有表

GRANT create ON schema schemaname TO dbuser;--给用户授予在schema上的create权限，比如create table、create view等

GRANT USAGE ON schema schemaname TO dbuser;

grant select on schema public to dbuser;--报错ERROR: invalid privilege type SELECT for schema

--USAGE：对于程序语言来说，允许使用指定的程序语言创建函数;对于Schema来说，允许查找该Schema下的对象;对于序列来说，允许使用currval和nextval函数;对于外部封装器来说，允许使用外部封装器来创建外部服务器;对于外部服务器来说，允许创建外部表。

select relname,n.amname as index_type from pg_class m,pg_am n where m.relam = n.oid and m.oid in

(select b.indexrelid from pg_class a,pg_index b where a.oid = b.indrelid and a.relname = 'cc');

SELECT c.relname,c2.relname, c2.relpages* as size_kb FROM pg_class c, pg_class c2, pg_index i

WHERE c.relname ='cc' AND c.oid =i.indrelid AND c2.oid =i.indexrelid ORDER BY c2.relname;

select b.indexrelid from pg_class a,pg_index b where a.oid = b.indrelid and a.relname = 'cc';

select pg_get_indexdef(b.indexrelid);

select oid,* from pg_proc where proname = 'insert_platform_action_exist'; --oid = 24610

select * from pg_get_functiondef();

select pg_relation_size('cc'); --368640 byte

select pg_size_pretty(pg_relation_size('cc')) --360 kB

SELECT pg_relation_filepath(oid), relpages FROM pg_class WHERE relname = 'empsalary';

apple=# select proname from pg_proc where proname like 'pg_%_lsn';

proname

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

pg_current_wal_flush_lsn

pg_current_wal_insert_lsn

pg_current_wal_lsn

pg_last_wal_receive_lsn

pg_last_wal_replay_lsn

apple=# select pg_current_wal_lsn();

pg_current_wal_lsn

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

0/45000098

select pg_walfile_name('0/1732DE8');

SELECT * FROM pg_walfile_name_offset(pg_current_wal_lsn());

select pg_switch_wal();

pg_archivecleanup /postgresql/pgsql/data/pg_wal 000000010000000000000005

表示删除000000010000000000000005之前的所有日志

--pg_wal日志没有设置保留周期的参数，即没有类似mysql的参数expire_logs_days，pg_wal日志永久保留，除非shell脚步删除几天前或pg-rman备份时候设置保留策略

select * from pg_replication_slots;