Over on [1] I noticed that the user had set force_parallel_mode to
"on" in the hope that would trick the planner into making their query
run more quickly. Of course, that's not what they want since that GUC
is only there to inject some parallel nodes into the plan in order to
verify the tuple communication works.
I get the idea that Robert might have copped some flak about this at
some point, given that he wrote the blog post at [2].
The user would have realised this if they'd read the documentation
about the GUC. However, I imagine they only went as far as finding a
GUC with a name which appears to be exactly what they need. I mean,
what else could force_parallel_mode possibly do?
Should we maybe rename it to something less tempting? Maybe
debug_parallel_query?
I wonder if \dconfig *parallel* is going to make force_parallel_mode
even easier to find once PG15 is out.
David
[1]
https://www.postgresql.org/message-id/DB4PR02MB8774E06D595D3088BE04ED92E7B99%40DB4PR02MB8774.eurprd02.prod.outlook.com
[2] https://www.enterprisedb.com/postgres-tutorials/using-forceparallelmode-correctly-postgresql
