Identificar tamanho do banco de dados

Como o PostgreSQL tem uma forma diferente de armazenar as informações, ou seja, não é um arquivo único, o comando abaixo auxilia na identificação do tamanho do banco de dados. 

SELECT
table_name nome_tabela,
pg_size_pretty(table_size)   || ' (' || CASE WHEN total_size = 0 THEN 0.00 ELSE round(table_size * 100 / total_size) END   || ' %)' AS tamanho_dados,
pg_size_pretty(indexes_size) || ' (' || CASE WHEN total_size = 0 THEN 0.00 ELSE round(indexes_size * 100 / total_size) END || ' %)' AS tamanho_indice,
pg_size_pretty(total_size)                                                                                                          AS tamanho_total
FROM (
(SELECT
table_name,
pg_table_size(table_name)          AS table_size,
pg_indexes_size(table_name)        AS indexes_size,
pg_total_relation_size(table_name) AS total_size
FROM (
SELECT ('"' || table_schema || '"."' || table_name || '"') AS table_name
FROM information_schema.tables
WHERE NOT table_schema IN ('pg_catalog', 'information_schema')
) AS all_tables
ORDER BY total_size DESC)
UNION ALL
(SELECT
'TOTAL',
sum(pg_table_size(table_name))          AS table_size,
sum(pg_indexes_size(table_name))        AS indexes_size,
sum(pg_total_relation_size(table_name)) AS total_size
FROM (
SELECT ('"' || table_schema || '"."' || table_name || '"') AS table_name
FROM information_schema.tables
WHERE NOT table_schema IN ('pg_catalog', 'information_schema')
) AS all_tables)
) AS pretty_sizes;