Query below return table which uses 50% of summary space used by all database tables.

Query

select schemaname as table_schema, 
       relname as table_name,
       pg_size_pretty(pg_relation_size(relid))
from pg_catalog.pg_statio_user_tables
where pg_relation_size(relid) > 0.5 * (
        select sum((pg_relation_size(relid)))
        from pg_catalog.pg_statio_user_tables);

Columns

• table_schema - name of schema
• table_name - name of table
• data_size - space used by table

Rows

• Query should return one row

Sample results