SQL, Postgres OIDs, What are they and why are they useful?

Question

I am looking at some PostgreSQL table creation and I stumbled upon this:

CREATE TABLE (
...
) WITH ( OIDS = FALSE );

I read the documentati

Answer 1

OIDs being phased out

The core team responsible for Postgres is gradually phasing out OIDs.

Postgres 12 removes special behavior of OID columns

The use of OID as an optional system column on your tables is now removed from Postgres 12. You can no longer use:

• CREATE TABLE … WITH OIDS command
• default_with_oids (boolean) compatibility setting

The data type OID remains in Postgres 12. You can explicitly create a column of the type OID.

After migrating to Postgres 12, any optionally-defined system column oid will no longer be invisible by default. Performing a SELECT * will now include this column. Note that this extra “surprise” column may break naïvely written SQL code.