Summary of default values in PostgreSQL database

Query below summarizes default constraints in a database listing all distinct default value definitions for columns with the number of their occurrence.


select column_default,
       count(distinct table_schema || '.' || table_name) as tables,
       count(column_name) as columns
from information_schema.columns
where table_schema not in ('pg_catalog', 'information_schema')
group by column_default
order by tables desc,
         columns desc;


  • column_default - definition of default constraint (formula) and NULL for columns without a default value
  • tables - number of tables with this constraint (or number of tables with columns with no constraints for NULL row)
  • columns - number of columns with this particular constraint (or no constraint for NULL row)


  • One row represents one unique definition of default value
  • Scope of rows: all distinct definitions of default column values in a database and one NULL row for columns without constraints
  • Ordered by the number of occurrences from the most popular

Sample results

Different default column definitions in pagila database:

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