Is it possible to get database name and size for all databases in my PostgreSQL database server?

Question

I have a PostgreSQL database server with multiple databases. I would like to select name, size for each database, like this:

| name |   size   |
-------------------
| db_1 | 21115439 |
| db_2 | 34238574 |
| db_3 | 83859902 |
| db_4 | 18447618 |

I know how to get one specific database size SELECT pg_database_size('db_1'), but is there any way to get multiple databases?

Answer 1

According to this site https://wiki.postgresql.org/wiki/Disk_Usage ;

SELECT d.datname as Name,  pg_catalog.pg_get_userbyid(d.datdba) as Owner,
    CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')
        THEN pg_catalog.pg_size_pretty(pg_catalog.pg_database_size(d.datname))
        ELSE 'No Access'
    END as Size
FROM pg_catalog.pg_database d
    order by
    CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')
        THEN pg_catalog.pg_database_size(d.datname)
        ELSE NULL
    END desc