CONSULTAR INFORMAÇÕES DO BANCO DE DADOS OU SCHEMA

PostgreSQL 8.0.0:

=> SELECT * FROM information_schema.tables
 Essa query busca todas informações sobre o banco a qual está conectado, ou seja, nome_db, nome_schema e nome_tabela.

=>SELECT * FROM information_schema.tables WHERE table_schema='nome_do_schema'
 Traz todas tabelas relacionadas ao schema informado nesta query.

=> SELECT current_database();

 current_database
------------------
 template1 

=> select schema_name from information_schema.schemata

 {retorna nome de todos schemas do banco que está conectado}

 => SELECT current_schema();

 current_schema
----------------
 public

=> SELECT current_schemas(TRUE);

   current_schemas
---------------------
 {pg_catalog,public}

=> SELECT CURRENT_USER AS usuario;

 usuario
----------
 postgres

=> SELECT inet_client_addr();

 inet_client_addr
------------------
 192.168.75.1

=> template1=# SELECT inet_client_port();

 inet_client_port
------------------
            16522

=> SELECT inet_server_addr();

 inet_server_addr
------------------
 192.168.75.128

=> SELECT inet_server_port();

 inet_server_port
------------------
             5432

=> SELECT SESSION_USER as usuario;

 usuario
----------
 postgres

=> SELECT USER as usuario;

 usuario
----------
 postgres

=> SELECT version() AS versao;

                                         versao
-----------------------------------------------------------------------------------------
 PostgreSQL 8.0.0 on i686-pc-mingw32, compiled by GCC gcc.exe (GCC) 3.4.2 (mingw-special)