PostgreSQL : List all primary keys

gistfile1.sql

SELECT a.attname AS pkey, c.relname as pkey_index_name, c2.relname AS table_name
FROM   pg_index i
JOIN   pg_attribute a ON a.attrelid = i.indrelid AND a.attnum = ANY(i.indkey)
JOIN   pg_catalog.pg_class c ON i.indexrelid = c.oid
JOIN  pg_catalog.pg_class c2 ON i.indrelid = c2.oid  
JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE i.indisprimary
AND n.nspname = 'public';