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| author | Robert Haas <rhaas@postgresql.org> | 2017-11-15 08:17:29 -0500 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2017-11-15 08:23:18 -0500 |
| commit | e5253fdc4f5fe2f38aec47e08c6aee93f934183d (patch) | |
| tree | b32d139116adab712dea0cb4ac02a939ff4aebd6 /src/backend/executor/nodeGather.c | |
| parent | 7518049980be1d90264addab003476ae105f70d4 (diff) | |
| download | postgresql-e5253fdc4f5fe2f38aec47e08c6aee93f934183d.tar.gz postgresql-e5253fdc4f5fe2f38aec47e08c6aee93f934183d.zip | |
Add parallel_leader_participation GUC.
Sometimes, for testing, it's useful to have the leader do nothing but
read tuples from workers; and it's possible that could work out better
even in production.
Thomas Munro, reviewed by Amit Kapila and by me. A few final tweaks
by me.
Discussion: http://postgr.es/m/CAEepm=2U++Lp3bNTv2Bv_kkr5NE2pOyHhxU=G0YTa4ZhSYhHiw@mail.gmail.com
Diffstat (limited to 'src/backend/executor/nodeGather.c')
| -rw-r--r-- | src/backend/executor/nodeGather.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/backend/executor/nodeGather.c b/src/backend/executor/nodeGather.c index 639f4f5af88..0298c65d065 100644 --- a/src/backend/executor/nodeGather.c +++ b/src/backend/executor/nodeGather.c @@ -38,6 +38,7 @@ #include "executor/nodeSubplan.h" #include "executor/tqueue.h" #include "miscadmin.h" +#include "optimizer/planmain.h" #include "pgstat.h" #include "utils/memutils.h" #include "utils/rel.h" @@ -73,7 +74,8 @@ ExecInitGather(Gather *node, EState *estate, int eflags) gatherstate->ps.ExecProcNode = ExecGather; gatherstate->initialized = false; - gatherstate->need_to_scan_locally = !node->single_copy; + gatherstate->need_to_scan_locally = + !node->single_copy && parallel_leader_participation; gatherstate->tuples_needed = -1; /* @@ -193,9 +195,9 @@ ExecGather(PlanState *pstate) node->nextreader = 0; } - /* Run plan locally if no workers or not single-copy. */ + /* Run plan locally if no workers or enabled and not single-copy. */ node->need_to_scan_locally = (node->nreaders == 0) - || !gather->single_copy; + || (!gather->single_copy && parallel_leader_participation); node->initialized = true; } |