Support Oid (Object Identifier Types)

[neverchanje]

Is your feature request related to a problem? Please describe.

Oid has become the common blocker for extending our supports to more PG ecosystem tools.
The idea is very simple - to support the oid type and its associated types, including regproc, regprocedure, regoper, regoperator, regclass, and regtype.

We don't have to support operations except for the type conversion from/to oid and text/varchar/regproc/regprocedure/regoper/regoperator/regclass/regtype.

from/to	text	oid	regproc	regprocedure	regoper	regoperator	regclass	regtype
text	t	t	t	t	t	t	t	t
oid	t	t	t	t	t	t	t	t
regproc	t	t	t	f	f	f	f	f
regprocedure	t	t	f	t	f	f	f	f
regoper	t	t	f	f	t	f	f	f
regoperator	t	t	f	f	f	t	f	f
regclass	t	t	f	f	f	f	t	f
regtype	t	t	f	f	f	f	f	t

Oid types should not be allowed to output in sinks.

Describe the solution you'd like

Solution 1:

Implementing oid as a pure alias of int32, and regproc/regprocedure/regoper/regoperator/regclass/regtype as an alias of text.

• Pros: Easy to implement.
• Cons: Unaligned with PG's behavior. In this case, as @xiangjinwu found, order by regproc would order by the text value, while PG's behavior is ordering based on the integer value (oid).

Solution 2:

Fully support these types in our type system.

• Pros: 100% aligned with PG's behavior.
• Cons: Implemention complexity is high.

Describe alternatives you've considered

No response

Additional context

This is not an urgent task, but worths some efforts once anyone have bandwidth.

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[xiangjinwu]

Will do a proof-of-concept in order to evaluate the feasibility of one approach I have in mind and have better understanding of the complexity of this issue.