The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/14/when-can-parallel-query-be-used.html
Description:
"In addition, the system must not be running in single-user mode. Since the
entire database system is running in single process in this situation, no
background workers will be available."
Source:
https://www.postgresql.org/docs/14/when-can-parallel-query-be-used.html