PostgreSQL adapter: failed to recognize types in pg_class table

[stanhu]

Steps to reproduce

Use Rails 6.0.3.3 with PostgreSQL and use the pg_class table:

class PgClass < ActiveRecord::Base
  self.table_name = 'pg_class'
  self.primary_key = 'oid'
end

PgClass.all

Expected behavior

No warning messages.

Actual behavior

unknown OID 28: failed to recognize type of 'relfrozenxid'. It will be treated as String.
unknown OID 1034: failed to recognize type of 'relacl'. It will be treated as String.
unknown OID 194: failed to recognize type of 'relpartbound'. It will be treated as String.

It looks like this error is coming from:

rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

Line 514 in 1db2ae1

warn "unknown OID #{oid}: failed to recognize type of '#{column_name}'. It will be treated as String."

# SELECT t.oid, t.typname, t.typelem, t.typdelim, t.typinput, r.rngsubtype, t.typtype, t.typbasetype
            FROM pg_type as t
            LEFT JOIN pg_range as r ON oid = rngtypid
 where oid IN (28, 1034,  194);
 oid  |   typname    | typelem | typdelim |    typinput     | rngsubtype | typtype | typbasetype 
------+--------------+---------+----------+-----------------+------------+---------+-------------
   28 | xid          |       0 | ,        | xidin           |            | b       |           0
  194 | pg_node_tree |       0 | ,        | pg_node_tree_in |            | b       |           0
 1034 | _aclitem     |    1033 | ,        | array_in        |            | b       |           0
(3 rows)

# \d+ pg_class;
                                         Table "pg_catalog.pg_class"
       Column        |     Type     | Collation | Nullable | Default | Storage  | Stats target | Description 
---------------------+--------------+-----------+----------+---------+----------+--------------+-------------
 oid                 | oid          |           | not null |         | plain    |              | 
 relname             | name         |           | not null |         | plain    |              | 
 relnamespace        | oid          |           | not null |         | plain    |              | 
 reltype             | oid          |           | not null |         | plain    |              | 
 reloftype           | oid          |           | not null |         | plain    |              | 
 relowner            | oid          |           | not null |         | plain    |              | 
 relam               | oid          |           | not null |         | plain    |              | 
 relfilenode         | oid          |           | not null |         | plain    |              | 
 reltablespace       | oid          |           | not null |         | plain    |              | 
 relpages            | integer      |           | not null |         | plain    |              | 
 reltuples           | real         |           | not null |         | plain    |              | 
 relallvisible       | integer      |           | not null |         | plain    |              | 
 reltoastrelid       | oid          |           | not null |         | plain    |              | 
 relhasindex         | boolean      |           | not null |         | plain    |              | 
 relisshared         | boolean      |           | not null |         | plain    |              | 
 relpersistence      | "char"       |           | not null |         | plain    |              | 
 relkind             | "char"       |           | not null |         | plain    |              | 
 relnatts            | smallint     |           | not null |         | plain    |              | 
 relchecks           | smallint     |           | not null |         | plain    |              | 
 relhasrules         | boolean      |           | not null |         | plain    |              | 
 relhastriggers      | boolean      |           | not null |         | plain    |              | 
 relhassubclass      | boolean      |           | not null |         | plain    |              | 
 relrowsecurity      | boolean      |           | not null |         | plain    |              | 
 relforcerowsecurity | boolean      |           | not null |         | plain    |              | 
 relispopulated      | boolean      |           | not null |         | plain    |              | 
 relreplident        | "char"       |           | not null |         | plain    |              | 
 relispartition      | boolean      |           | not null |         | plain    |              | 
 relrewrite          | oid          |           | not null |         | plain    |              | 
 relfrozenxid        | xid          |           | not null |         | plain    |              | 
 relminmxid          | xid          |           | not null |         | plain    |              | 
 relacl              | aclitem[]    |           |          |         | extended |              | 
 reloptions          | text[]       | C         |          |         | extended |              | 
 relpartbound        | pg_node_tree | C         |          |         | extended |              | 
Indexes:
    "pg_class_oid_index" UNIQUE, btree (oid)
    "pg_class_relname_nsp_index" UNIQUE, btree (relname, relnamespace)
    "pg_class_tblspc_relfilenode_index" btree (reltablespace, relfilenode)
Access method: heap

Do we just need to register these manually?

For example, relfrozenxid has been around for a while: https://www.postgresql.org/docs/9.5/routine-vacuuming.html

System configuration

Rails version: 6.0.3.3

Ruby version: 2.7.2

[composerinteralia]

You can see all the registered types in

rails/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

Line 520 in 2066d64

def initialize_type_map(m = type_map)

Or alternately, you could take a peek at:

ActiveRecord::Base.connection.send(:type_map).keys

Either way it looks like those particular types are not registered. I don't really know enough about them to be able to say whether that is intentional, but I am sort of guessing it is and that we only register types available to users like those documented on https://www.postgresql.org/docs/13/datatype.html

We do handle array types like 1034/_aclitem in load_additional_types via the TypeMapInitializer, but that only works if the subtype (i.e. 1033/aclitem) is already registered.

You could certainly register the xid, pg_node_tree, and aclitem types manually in your own application.

[stanhu]

Thanks, I'll close this issue then unless you think it would be helpful to have in Rails.