PG数据库常用命令

查看帮助命令DB=# help --总的帮助DB=# \h --SQL commands级的帮助DB=# \? --psql commands级的帮助

按列显示，类似MySQL的\GDB=# \xExpanded display is on.

查看DB安装目录(最好root用户执行)find / -name initdb

查看有多少DB实例在运行(最好root用户执行)find / -name postgresql.conf

查看DB版本cat $PGDATA/PG_VERSIONpsql --versionDB=# show server_version;DB=# select version();

查看DB实例运行状态pg_ctl status

查看所有数据库psql –l --查看5432端口下面有多少个DBpsql –p XX –l --查看XX端口下面有多少个DBDB=# \lDB=# select * from pg_database;

创建数据库createdb database_nameDB=# \h create database --创建数据库的帮助命令DB=# create database database_name

进入某个数据库psql –d dbnameDB=# \c dbname

查看当前数据库DB=# \cDB=# select current_database();

查看数据库文件目录DB=# show data_directory;cat $PGDATA/postgresql.conf |grep data_directorycat /etc/init.d/postgresql|grep PGDATA=lsof |grep 5432得出第二列的PID号再ps –ef|grep PID

查看表空间select * from pg_tablespace;

查看语言select * from pg_language;

查询所有schema，必须到指定的数据库下执行select * from information_schema.schemata;SELECT nspname FROM pg_namespace;\dnS

查看表名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';

查看表结构查看表结构DB=# \d tablenameDB=# select * from information_schema.columns where table_schema='public' and table_name='XX';

查看索引DB=# \diDB=# select * from pg_index;

查看视图DB=# \dvDB=# select * from pg_views where schemaname = 'public';DB=# select * from information_schema.views where table_schema = 'public';

查看触发器DB=# select * from information_schema.triggers;

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

查看约束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';

查看XX数据库的大小SELECT pg_size_pretty(pg_database_size('XX')) As fulldbsize;

查看所有数据库的大小select pg_database.datname, pg_size_pretty (pg_database_size(pg_database.datname)) AS size from pg_database;

查看各数据库数据创建时间：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;

按占空间大小，顺序查看所有表的大小select relname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_tables where schemaname='public' order by pg_relation_size(relid) desc;

按占空间大小，顺序查看索引大小select indexrelname, pg_size_pretty(pg_relation_size(relid)) from pg_stat_user_indexes where schemaname='public' order by pg_relation_size(relid) desc;

查看参数文件DB=# show config_file;DB=# show hba_file;DB=# show ident_file;

查看当前会话的参数值DB=# show all;

查看参数值select * from pg_file_settings

查看某个参数值,比如参数work_memDB=# show work_mem

修改某个参数值,比如参数work_memDB=# 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。

查看是否归档DB=# show archive_mode;

查看运行日志的相关配置，运行日志包括Error信息，定位慢查询SQL，数据库的启动关闭信息，checkpoint过于频繁等的告警信息。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

查看wal日志的配置，wal日志就是redo重做日志存放在data_directory/pg_wal目录

查看当前用户DB=# \cDB=# select current_user;

查看所有用户DB=# select * from pg_user;DB=# select * from pg_shadow;

查看所有角色DB=# \duDB=# select * from pg_roles;

查询用户XX的权限，必须到指定的数据库下执行select * from information_schema.table_privileges where grantee='XX';

创建用户XX，并授予超级管理员权限create user XXX SUPERUSER PASSWORD '123456'

创建角色，赋予了login权限，则相当于创建了用户，在pg_user可以看到这个角色create role "user1" superuser;--pg_roles有user1，pg_user和pg_shadow没有user1alter role "user1" login;--pg_user和pg_shadow也有user1了

授权DB=# \h grantGRANT 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。

查看表上存在哪些索引以及大小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*8 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;

查看索引定义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);

查看过程函数定义select oid,* from pg_proc where proname = 'insert_platform_action_exist'; --oid = 24610select * from pg_get_functiondef(24610);

查看表大小(不含索引等信息)select pg_relation_size('cc'); --368640 byteselect pg_size_pretty(pg_relation_size('cc')) --360 kB

查看表所对应的数据文件路径与大小SELECT pg_relation_filepath(oid), relpages FROM pg_class WHERE relname = 'empsalary';

posegresql查询当前lsn1、用到哪些方法：apple=# select proname from pg_proc where proname like 'pg_%_lsn';proname---------------------------------pg_current_wal_flush_lsnpg_current_wal_insert_lsnpg_current_wal_lsnpg_last_wal_receive_lsnpg_last_wal_replay_lsn

2、查询当前的lsn值：apple=# select pg_current_wal_lsn();pg_current_wal_lsn--------------------------0/45000098

3、查询当前lsn对应的日志文件select pg_walfile_name('0/1732DE8');

4、查询当前lsn在日志文件中的偏移量SELECT * FROM pg_walfile_name_offset(pg_current_wal_lsn());

切换pg_wal日志select pg_switch_wal();

清理pg_wal日志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

查询有哪些slot，任意一个数据库下都可以查，查询的结果都一样select * from pg_replication_slots;