Add support for REGCLASSOID type

[Y--]

Small QoL PR that does two minor thing:

• shows the Oid when the type in unsupported
• add mapping for PG's REGCLASSOID type

[wuputah]

Could you please add a test case for this type? Once that's done, lgtm!

[Tishj]

That works, do keep in mind that this means we lose the context of what this was on the postgres side this way.
We'd need something similar to what we do for NumericAsDouble to differentiate between an actual INT4 and a REGCLASSOID

[Y--]

Yeah definitely. I added this because it was useful for me debugging internals but agree that we're losing information here.

[hlinnaka]

OIDs are unsigned, so this goes wrong:

postgres=# create table x (cls regclass);
CREATE TABLE
postgres=# insert into x values (3_000_000_000);
INSERT 0 1
postgres=# select * from x;
    cls     
------------
 3000000000
(1 row)

postgres=# SET duckdb.execution TO true;
SET
postgres=# select * from x;
     cls     
-------------
 -1294967296
(1 row)

[Y--]

OIDs are unsigned, so this goes wrong:

postgres=# create table x (cls regclass);
CREATE TABLE
postgres=# insert into x values (3_000_000_000);
INSERT 0 1
postgres=# select * from x;
    cls     
------------
 3000000000
(1 row)

postgres=# SET duckdb.execution TO true;
SET
postgres=# select * from x;
     cls     
-------------
 -1294967296
(1 row)

Thanks for catching this! I'll work on this ASAP

[Y--]

Will be fixed here: #125