Add has_check() Variants

[theory]

has_check() is currently quite limited. It should be updated to have the same interface as has_index().

[theory]

There should be a check_ok() function, too. It should be similar to fk_ok(). Query to get started:

SELECT pg_catalog.pg_get_constraintdef(r.oid, true)
  FROM pg_catalog.pg_namespace n
  JOIN pg_catalog.pg_class c       ON n.oid = c.relnamespace
  JOIN pg_catalog.pg_constraint x  ON c.oid = x.conrelid
 WHERE n.nspname = $1
   AND c.relname = $2
   AND x.contype = 'c'
   AND x.conname = $3

[keithf4]

A request for renewed interest in getting this enchancement. Could use it for constraint stuff in pg_partman.

[theory]

Got a pull request?

[keithf4]

Wish I had the time. Just letting you know there is interest in this feature. :)