How many tables don't have primary keys (with percentage) in PostgreSQL database

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.


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;


  • 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


Query returns just one row.

Sample results

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