CREATE TABLE without AS doesn't have anything to parallelize.
The query writes any data or locks any database rows. If a query
contains a data-modifying operation either at the top level or within
a CTE, no parallel plans for that query will be generated. As an
- exception, the commands CREATE TABLE, SELECT
+ exception, the commands CREATE TABLE ... AS, SELECT
INTO, and CREATE MATERIALIZED VIEW which create a new
table and populate it can use a parallel plan.