Размеры таблиц и баз в PostgreSQL

Размер самых больших баз в кластере

select 
datname, 
pg_size_pretty(pg_database_size(datname)) as size_pretty, 
pg_database_size(datname) as size_bytes
from pg_database
order by size_bytes desc

Размер самых больших таблиц в базе с индексами

select
table_name,
pg_size_pretty(table_size) AS table_size,
pg_size_pretty(indexes_size) AS indexes_size,
pg_size_pretty(total_size) AS total_size
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
) AS all_tables
ORDER BY total_size DESC
) AS pretty_sizes