--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/postgres.rst	Thu Dec 13 09:55:01 2018 +0200
@@ -0,0 +1,124 @@
+.. -*- coding: utf-8; -*-
+
+==========
+ Postgre.
+==========
+.. contents::
+   :local:
+
+Installing on Debian.
+=====================
+
+Install and create new user and database::
+
+  $ sudo apt-get install postgresql postgresql-client
+  $ sudo su - postgres
+  % psql
+  postgres=# CREATE USER "mypguser" WITH PASSWORD 'mypguserpass';
+  postgres=# CREATE DATABASE "mypgdatabase" OWNER "mypguser";
+  postgres=# \q
+
+Connect as user ``mypguser`` to new database::
+
+  $ su - mypguser
+  $ psql mypgdatabase
+
+In order to create local host superuser::
+
+  $ sudo su - postgres
+  $ createuser --superuser USER
+  $ exit
+  $ sudo -u USER psql
+
+..
+
+https://wiki.debian.org/PostgreSql
+  Debian wiki instructions.
+
+List databases, schemas and tables.
+===================================
+
+Default database is ``postgres``.
+
+To list databases and database locales::
+
+  $ psql -U pgadmin -l
+
+or::
+
+  => SELECT datname FROM pg_database WHERE datistemplate = false;
+  => \l
+
+To switch databases::
+
+  => \connect NAME
+
+Schemas::
+
+  => select schema_name from information_schema.schemata;
+  => select nspname from pg_catalog.pg_namespace;
+  => \dn *
+
+To list all tables in the current database::
+
+  => SELECT table_schema,table_name FROM information_schema.tables ORDER BY table_schema,table_name;
+  => \dt
+
+Set default schema.
+===================
+::
+
+  set search_path to NAME;
+
+Database, table, index size.
+============================
+
+Database size::
+
+  SELECT pg_database_size('geekdb');  -- in bytes
+  SELECT pg_size_pretty(pg_database_size('dbname'));
+
+List of databases sizes::
+
+  \l+
+
+List tables sizes::
+
+  \d+
+
+Table total size (with indexes)::
+
+  SELECT pg_size_pretty(pg_total_relation_size('schemaname.tablename'));
+
+Sole table size (without indexes and other)::
+
+  SELECT pg_size_pretty(pg_relation_size('schemaname.tablename'));
+
+Largest table in the PostgreSQL database::
+
+  SELECT relname, relpages FROM pg_class ORDER BY relpages DESC;
+
+Using psql client.
+==================
+
+Using password file ``~/.pgpass``::
+
+  # comment
+  hostname:port:database:username:password
+  hostname:port:*:username:password
+  hostname:*:*:username:password
+
+Connect by::
+
+  $ psql -U $USER -h $HOST  $SCHEMA
+
+How to view execution plan::
+
+  EXPLAIN query;
+  EXPLAIN ANALYZE query;
+
+How to redirect the output of query to a file::
+
+  \o output_file
+  SELECT * FROM pg_class;
+