Postgres: Report how close each table primary key is to its limit

tables_approaching_limit.sql

WITH column_info AS (
  SELECT t.relname AS table_name, c.attname AS column_name, c.atttypid, c.attlen AS length, y.typname AS type
         , pg_get_expr(adbin, adrelid) AS default
         , (regexp_matches(pg_get_expr(adbin, adrelid), 'nextval..(.*).::regclass'))[1] AS sequencename
  FROM pg_class t
  LEFT OUTER JOIN pg_attribute c ON c.attrelid = t.oid
  LEFT OUTER JOIN pg_type y ON y.oid = c.atttypid
  LEFT OUTER JOIN pg_attrdef d ON t.oid = d.adrelid AND d.adnum = c.attnum
  WHERE pg_get_expr(adbin, adrelid) LIKE '%nextval%'
),
max_values(length, max_value) AS (VALUES (4, 2147483647), (8, 9223372036854775807)),
sequence_info AS (
  SELECT table_name, column_name
       , (s.last_value * 100 / m.max_value) percent_of_limit
  FROM column_info ci
  JOIN pg_sequences s ON s.sequencename = ci.sequencename
  JOIN max_values m ON m.length = ci.length
  WHERE s.last_value IS NOT NULL
)
SELECT (table_name || '.' || column_name) AS name,
      percent_of_limit || '%' AS percent
FROM sequence_info
ORDER BY percent_of_limit DESC
LIMIT 10;