postgres
diff --git a/‎src/backend/executor/execParallel.c
Lines changed: 38 additions & 13 deletions b/‎src/backend/executor/execParallel.c
Lines changed: 38 additions & 13 deletions
diff --git a/‎src/test/regress/expected/select_parallel.out
Lines changed: 21 additions & 0 deletions b/‎src/test/regress/expected/select_parallel.out
Lines changed: 21 additions & 0 deletions
diff --git a/‎src/test/regress/sql/select_parallel.sql
Lines changed: 7 additions & 0 deletions b/‎src/test/regress/sql/select_parallel.sql
Lines changed: 7 additions & 0 deletions
@@ -808,6 +808,19 @@ ExecParallelReinitialize(PlanState *planstate,
 	/* Old workers must already be shut down */
 	Assert(pei->finished);
 
+	/* Clear the instrumentation space from the last round. */
+	if (pei->instrumentation)
+	{
+		Instrumentation *instrument;
+		SharedExecutorInstrumentation *sh_instr;
+		int			i;
+
+		sh_instr = pei->instrumentation;
+		instrument = GetInstrumentationArray(sh_instr);
+		for (i = 0; i < sh_instr->num_workers * sh_instr->num_plan_nodes; ++i)
+			InstrInit(&instrument[i], pei->planstate->state->es_instrument);
+	}
+
 	/* Force parameters we're going to pass to workers to be evaluated. */
 	ExecEvalParamExecParams(sendParams, estate);
 
@@ -925,21 +938,33 @@ ExecParallelRetrieveInstrumentation(PlanState *planstate,
 	for (n = 0; n < instrumentation->num_workers; ++n)
 		InstrAggNode(planstate->instrument, &instrument[n]);
 
-	/*
-	 * Also store the per-worker detail.
-	 *
-	 * Worker instrumentation should be allocated in the same context as the
-	 * regular instrumentation information, which is the per-query context.
-	 * Switch into per-query memory context.
-	 */
-	oldcontext = MemoryContextSwitchTo(planstate->state->es_query_cxt);
-	ibytes = mul_size(instrumentation->num_workers, sizeof(Instrumentation));
-	planstate->worker_instrument =
-		palloc(ibytes + offsetof(WorkerInstrumentation, instrument));
-	MemoryContextSwitchTo(oldcontext);
+	if (!planstate->worker_instrument)
+	{
+		/*
+		 * Allocate space for the per-worker detail.
+		 *
+		 * Worker instrumentation should be allocated in the same context as
+		 * the regular instrumentation information, which is the per-query
+		 * context. Switch into per-query memory context.
+		 */
+		oldcontext = MemoryContextSwitchTo(planstate->state->es_query_cxt);
+		ibytes =
+			mul_size(instrumentation->num_workers, sizeof(Instrumentation));
+		planstate->worker_instrument =
+			palloc(ibytes + offsetof(WorkerInstrumentation, instrument));
+		MemoryContextSwitchTo(oldcontext);
+
+		for (n = 0; n < instrumentation->num_workers; ++n)
+			InstrInit(&planstate->worker_instrument->instrument[n],
+					  planstate->state->es_instrument);
+	}
 
 	planstate->worker_instrument->num_workers = instrumentation->num_workers;
-	memcpy(&planstate->worker_instrument->instrument, instrument, ibytes);
+
+	/* Accumulate the per-worker detail. */
+	for (n = 0; n < instrumentation->num_workers; ++n)
+		InstrAggNode(&planstate->worker_instrument->instrument[n],
+					 &instrument[n]);
 
 	/* Perform any node-type-specific work that needs to be done. */
 	switch (nodeTag(planstate))
 
@@ -378,7 +378,28 @@ select count(*) from bmscantest where a>1;
  99999
 (1 row)
 
+-- test accumulation of stats for parallel node
 reset enable_seqscan;
+alter table tenk2 set (parallel_workers = 0);
+explain (analyze, timing off, summary off, costs off)
+	select count(*) from tenk1, tenk2 where tenk1.hundred > 1
+        and tenk2.thousand=0;
+                                QUERY PLAN                                
+--------------------------------------------------------------------------
+ Aggregate (actual rows=1 loops=1)
+   ->  Nested Loop (actual rows=98000 loops=1)
+         ->  Seq Scan on tenk2 (actual rows=10 loops=1)
+               Filter: (thousand = 0)
+               Rows Removed by Filter: 9990
+         ->  Gather (actual rows=9800 loops=10)
+               Workers Planned: 4
+               Workers Launched: 4
+               ->  Parallel Seq Scan on tenk1 (actual rows=1960 loops=50)
+                     Filter: (hundred > 1)
+                     Rows Removed by Filter: 40
+(11 rows)
+
+alter table tenk2 reset (parallel_workers);
 reset enable_indexscan;
 reset enable_hashjoin;
 reset enable_mergejoin;
 
@@ -149,7 +149,14 @@ insert into bmscantest select r, 'fooooooooooooooooooooooooooooooooooooooooooooo
 create index i_bmtest ON bmscantest(a);
 select count(*) from bmscantest where a>1;
 
+-- test accumulation of stats for parallel node
 reset enable_seqscan;
+alter table tenk2 set (parallel_workers = 0);
+explain (analyze, timing off, summary off, costs off)
+	select count(*) from tenk1, tenk2 where tenk1.hundred > 1
+        and tenk2.thousand=0;
+alter table tenk2 reset (parallel_workers);
+
 reset enable_indexscan;
 reset enable_hashjoin;
 reset enable_mergejoin;