Sunday, June 20, 2010

Postgresql Basic Commands

Login to postgresql:
psql -d mydb -U myuser -W
psql -h myhost -d mydb -U myuser -W
psql -U myuser -h myhost "dbname=mydb sslmode=require" # ssl connection

Default Admin Login:
sudo -u postgres psql -U postgres
sudo -u postgres psql

List databases on postgresql server:
psql -l [-U myuser] [-W]

Turn off line pager pagination in psql:
\pset pager

Determine system tables:
select * from pg_tables where tableowner = 'postgres';

List databases from within a pg shell:
\l

List databases from UNIX command prompt:
psql -U postgres -l

Describe a table:
\d tablename

Quit psql:
\q

Switch postgres database within admin login shell:
\connect databasename

Reset a user password as admin:
alter user usertochange with password 'new_passwd';

Show all tables:
\dt

List all Schemas:
\dn

List all users:
\du

Load data into posgresql:
psql -W -U username -H hostname < file.sql

Dump (Backup) Data into file:
pg_dump -W -U username -h hostname database_name > file.sql

Increment a sequence:
SELECT nextval('my_id_seq');

Create new user:
CREATE USER jjasinski WITH PASSWORD 'myPassword';
# or
sudo -u postgres createuser jjasinski -W

Change user password:
ALTER USER Postgres WITH PASSWORD 'mypass';

Grant user createdb privilege:
ALTER USER myuser WITH createdb;

Create a superuser user:
create user mysuper with password '1234' SUPERUSER
# or even better
create user mysuper with password '1234' SUPERUSER CREATEDB CREATEROLE INHERIT LOGIN REPLICATION;
# or
sudo -u postgres createuser jjasinski -W -s

Upgrade an existing user to superuser: 
alter user mysuper with superuser;
# or even better
alter user mysuper with SUPERUSER CREATEDB CREATEROLE INHERIT LOGIN REPLICATION

Show Database Version:
SELECT version();

Change Database Owner:
alter database database_name owner to new_owner;

Copy a database:
CREATE DATABASE newdb WITH TEMPLATE originaldb;
http://www.commandprompt.com/ppbook/x14316

View Database Connections:
SELECT * FROM pg_stat_activity;

View show data directory (works on 9.1+; not on 7.x):
show data_directory;

Show run-time parameters:
show all;
select * from pg_settings;

Show the block size setting:
# show block_size;
 block_size
------------
 8192
(1 row)

Show stored procedure source:
SELECT prosrc FROM pg_proc WHERE proname = 'procname'

Grant examples:
# readonly to all tables for myuser
grant select on all tables in schema public to myuser;
# all privileges on table1 and table2 to myuser
grant all privileges on table1, table2, table3 to myuser;

Restore Postgres .dump file:
pg_restore --verbose --clean --no-acl --no-owner -h localhost -U myuser -d mydb latest.dump
source

Find all active sessions and kill them (i.e. for when needing to drop or rename db)
Source: http://stackoverflow.com/questions/5408156/how-to-drop-a-postgresql-database-if-there-are-active-connections-to-it

# Postgres 9.2 and above
SELECT pg_terminate_backend(pg_stat_activity.pid) 
FROM pg_stat_activity 
WHERE pg_stat_activity.datname = 'TARGET_DB' 
 AND pid <> pg_backend_pid();

# Postgres 9.1 and below
SELECT pg_terminate_backend(pg_stat_activity.procpid) 
FROM pg_stat_activity 
WHERE pg_stat_activity.datname = 'TARGET_DB' 
AND procpid <> pg_backend_pid();


Re-read postgres config without dropping connections (i.e. if postgres.conf or pg_hba.conf changes)
Source: http://www.heatware.net/databases/postgresql-reload-config-without-restarting/

/usr/bin/pg_ctl reload
or
SELECT pg_reload_conf();

Per user query logging (logs to to postgres logs):
alter role myuser set log_statement = 'all';


Sources:
http://www.devdaily.com/blog/post/postgresql/log-in-postgresql-database
http://forums.devshed.com/postgresql-help-21/how-do-you-turn-off-more-scroll-lock-at-psql-174831.htm
http://www.cyberciti.biz/faq/howto-add-postgresql-user-account/
http://archives.postgresql.org/pgsql-general/1998-08/msg00050.php
http://stackoverflow.com/questions/876522/creating-a-copy-of-a-database-in-postgres
http://stackoverflow.com/questions/1137060/where-does-postgresql-store-the-database

2 comments:

Sagar R said...

I really appreciate information shared above. It’s of great help. If someone want to learn Online (Virtual) instructor lead live training in Postgresql Admin
, kindly contact us http://www.maxmunus.com/contact
MaxMunus Offer World Class Virtual Instructor led training on in Postgresql Admin We have industry expert trainer. We provide Training Material and Software Support. MaxMunus has successfully conducted 100000+ trainings in India, USA, UK, Australlia, Switzerland, Qatar, Saudi Arabia, Bangladesh, Bahrain and UAE etc.
For Demo Contact us:
Name : Arunkumar U
Email : arun@maxmunus.com
Skype id: training_maxmunus
Contact No.-+91-9738507310
Company Website –http://www.maxmunus.com


Deepika vs said...

I really appreciate information shared above. It’s of great help. If someone want to learn Online (Virtual) instructor lead live training in TECHNOLOGY , kindly contact us http://www.maxmunus.com/contact
MaxMunus Offer World Class Virtual Instructor led training on TECHNOLOGY. We have industry expert trainer. We provide Training Material and Software Support. MaxMunus has successfully conducted 100000+ trainings in India, USA, UK, Australlia, Switzerland, Qatar, Saudi Arabia, Bangladesh, Bahrain and UAE etc.
For Demo Contact us.
Sangita Mohanty
MaxMunus
E-mail: sangita@maxmunus.com
Skype id: training_maxmunus
Ph:(0) 9738075708 / 080 - 41103383
http://www.maxmunus.com/