def safe_make_column_not_nullable(table, column)
    unsafe_execute "ALTER TABLE #{table} ADD CONSTRAINT tmp_not_null_constraint CHECK (#{column} IS NOT NULL) NOT VALID"
    unsafe_execute "ALTER TABLE #{table} VALIDATE CONSTRAINT tmp_not_null_constraint"
    unsafe_execute "ALTER TABLE #{table} ALTER COLUMN #{column} SET NOT NULL"
    unsafe_execute "ALTER TABLE #{table} DROP CONSTRAINT tmp_not_null_constraint"
  end