Subject: Any reason to keep HEAP_HASOID_OLD?

From: David Rowley <[email-masked]>
Date: Tue, 28 Apr 2026 16:27:59 +1200

Andres mentioned to me that I might want to look at
HeapTupleHeaderGetOidOld() as there's a comment and some code there
that would lead you to believe we can still have tuples with oids. If
that were true, the code I recently added for getting 'tp' in
slot_selectively_deform_heap_tuple() is wrong.

#define HEAP_HASOID_OLD 0x0008 /* has an object-id field */

On 11.22, I tried:

create extension pageinspect;
create table t1 (a int) with oids;
insert into t1 select generate_Series(1,1000);
select count(*) from heap_page_items(get_raw_page('public.t1',0))
where t_infomask & 8 <> 0;

 count
-------
   185

alter table t1 set without oids;

select count(*) from heap_page_items(get_raw_page('public.t1',0))
where t_infomask & 8 <> 0;
 count
-------
     0

And also, if I try to pg_upgrade before SET WITHOUT OIDS, I get:

$ pg_upgrade -d pgdata11 -D pgdata -b ~/pg11/bin -B ~/pg/bin
Performing Consistency Checks
-----------------------------
Checking cluster versions                                   ok
Checking database user is the install user                  ok
Checking database connection settings                       ok
Checking for prepared transactions                          ok
Checking for system-defined composite types in user tables  ok
Checking for reg* data types in user tables                 ok
Checking for contrib/isn with bigint-passing mismatch       ok
Checking for user-defined encoding conversions              ok
Checking for user-defined postfix operators                 ok
Checking for incompatible polymorphic functions             ok
Checking for tables WITH OIDS                               fatal

So, I'm not following how we could get a tuple with OIDs in versions after 11.

Should we get rid of HEAP_HASOID_OLD and the code that relates to it?

David

---

From: Andres Freund <[email-masked]>
Date: Tue, 28 Apr 2026 10:27:32 -0400

Hi,

> where t_infomask & 8 <> 0;

Yea, it seems we've started rewriting tables for SET WITHOUT OIDS a long time
ago:
	/*
	 * If we dropped the OID column, must adjust pg_class.relhasoids and tell
	 * Phase 3 to physically get rid of the column.  We formerly left the
	 * column in place physically, but this caused subtle problems.  See
	 * http://archives.postgresql.org/pgsql-hackers/2009-02/msg00363.php
	 */
	if (attnum == ObjectIdAttributeNumber)

I also verified that we don't allow SET WITHOUT OIDS when it's used as a row
type in another table.

> Performing Consistency Checks

I don't see it either.  Wonder why I / decided to leave it :/.

> Should we get rid of HEAP_HASOID_OLD and the code that relates to it?

Looks like it.

Greetings,

Andres Freund