Table Size Query

SELECT
    table_schema,
    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_schema,
        table_name,
        pg_table_size(fmt_table_name) AS table_size,
        pg_indexes_size(fmt_table_name) AS indexes_size,
        pg_total_relation_size(fmt_table_name) AS total_size
    FROM (
        SELECT
            ('"' || table_schema || '"."' || table_name || '"') AS fmt_table_name,
            table_schema,
            table_name
        FROM information_schema.tables
    ) AS all_tables
) AS pretty_sizes;

Schema sizes

SELECT
    schema_name,
    pg_size_pretty(SUM(total_size))   AS total_size
FROM (
    /* Get sizes for each table in the database */
    SELECT
        table_schema AS schema_name,
        pg_table_size(fmt_table_name)         AS table_size,
        pg_indexes_size(fmt_table_name)       AS indexes_size,
        pg_total_relation_size(fmt_table_name) AS total_size
    FROM (
        /* Build the fully-qualified table name */
        SELECT
            ('"' || table_schema || '"."' || table_name || '"') AS fmt_table_name,
            table_schema,
            table_name
        FROM information_schema.tables
        /* Optionally exclude system schemas here (like 'pg_catalog', 'information_schema') */
        WHERE table_schema NOT IN ('pg_catalog', 'information_schema')
    ) AS all_tables
) AS table_sizes
GROUP BY schema_name
ORDER BY SUM(total_size) DESC;