This query listed tables without primary keys and this one shows how many of them there are and what is the percentage of total tables.

Query

select sum.tables,
       sum.tables - pk.pk_count as no_pk_tables,
       round(100.0* (sum.tables - pk.pk_count) / sum.tables,2) ||'%'
             as no_pk_percent
from (select count(*) as tables
      from information_schema.tables tab
      where tab.table_type = 'BASE TABLE'
            and tab.table_schema not in ('pg_catalog', 'information_schema'))
      as sum
left join(
          select count(*) as pk_count
          from information_schema.tables tab
          join information_schema.table_constraints tco
               on tab.table_schema = tco.table_schema
               and tab.table_name = tco.table_name
               and tco.constraint_type = 'PRIMARY KEY'
          where tab.table_type = 'BASE TABLE'
          and tab.table_schema not in ('pg_catalog', 'information_schema')
) pk on true;

Columns

• tables - number of all tables in a database
• no_pk_tables - number of tables without a primary key
• no_pk_percent - percentage of tables without primary key in all tables

Rows

Query returns just one row.

Sample results