how to calculate current database size in postgresql code example

Example 1: how to get the size of the database in postgresql

SELECT pg_size_pretty( pg_database_size('dbname') );

Example 2: find size of all DB's postgres

CopySELECT pg_database.datname as "database_name", pg_database_size(pg_database.datname)/1024/1024 AS size_in_mb FROM pg_database ORDER by size_in_mb DESC;