Rename force_parallel_mode to debug_parallel_query

force_parallel_mode is meant to be used to allow us to exercise the
parallel query infrastructure to ensure that it's working as we expect.
It seems some users think this GUC is for forcing the query planner into
picking a parallel plan regardless of the costs.  A quick look at the
documentation would have made them realize that they were wrong, but the
GUC is likely too conveniently named which, evidently, seems to often
result in users expecting that it forces the planner into usefully
parallelizing queries.

Here we rename the GUC to something which casual users are less likely to
mistakenly think is what they need to make their query run more quickly.

For now, the old name can still be used.  We'll revisit if the old name
mapping can be removed once the buildfarm configs are all updated.

Reviewed-by: John Naylor
Discussion: https://postgr.es/m/CAApHDvrsOi92_uA7PEaHZMH-S4Xv+MGhQWA+GrP8b1kjpS1HjQ@mail.gmail.com

1 files changed, 2 insertions, 2 deletions

diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c
index 4c17407e5df..7afd434c601 100644
--- a/src/backend/optimizer/plan/planmain.c
+++ b/src/backend/optimizer/plan/planmain.c
@@ -114,12 +114,12 @@ query_planner(PlannerInfo *root,
 				 * Anything parallel-restricted in the query tlist will be
 				 * dealt with later.)  This is normally pretty silly, because
 				 * a Result-only plan would never be interesting to
-				 * parallelize.  However, if force_parallel_mode is on, then
+				 * parallelize.  However, if debug_parallel_query is on, then
 				 * we want to execute the Result in a parallel worker if
 				 * possible, so we must do this.
 				 */
 				if (root->glob->parallelModeOK &&
-					force_parallel_mode != FORCE_PARALLEL_OFF)
+					debug_parallel_query != DEBUG_PARALLEL_OFF)
 					final_rel->consider_parallel =
 						is_parallel_safe(root, parse->jointree->quals);