1 files changed, 94 insertions, 2 deletions

diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index e6635233155..f464cca9507 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -92,6 +92,7 @@ IndexOnlyNext(IndexOnlyScanState *node)
 		scandesc = index_beginscan(node->ss.ss_currentRelation,
 								   node->ioss_RelationDesc,
 								   estate->es_snapshot,
+								   &node->ioss_Instrument,
 								   node->ioss_NumScanKeys,
 								   node->ioss_NumOrderByKeys);
 
@@ -414,6 +415,27 @@ ExecEndIndexOnlyScan(IndexOnlyScanState *node)
 	}
 
 	/*
+	 * When ending a parallel worker, copy the statistics gathered by the
+	 * worker back into shared memory so that it can be picked up by the main
+	 * process to report in EXPLAIN ANALYZE
+	 */
+	if (node->ioss_SharedInfo != NULL && IsParallelWorker())
+	{
+		IndexScanInstrumentation *winstrument;
+
+		Assert(ParallelWorkerNumber <= node->ioss_SharedInfo->num_workers);
+		winstrument = &node->ioss_SharedInfo->winstrument[ParallelWorkerNumber];
+
+		/*
+		 * We have to accumulate the stats rather than performing a memcpy.
+		 * When a Gather/GatherMerge node finishes it will perform planner
+		 * shutdown on the workers.  On rescan it will spin up new workers
+		 * which will have a new IndexOnlyScanState and zeroed stats.
+		 */
+		winstrument->nsearches += node->ioss_Instrument.nsearches;
+	}
+
+	/*
 	 * close the index relation (no-op if we didn't open it)
 	 */
 	if (indexScanDesc)
@@ -707,11 +729,21 @@ ExecIndexOnlyScanEstimate(IndexOnlyScanState *node,
 						  ParallelContext *pcxt)
 {
 	EState	   *estate = node->ss.ps.state;
+	bool		instrument = (node->ss.ps.instrument != NULL);
+	bool		parallel_aware = node->ss.ps.plan->parallel_aware;
+
+	if (!instrument && !parallel_aware)
+	{
+		/* No DSM required by the scan */
+		return;
+	}
 
 	node->ioss_PscanLen = index_parallelscan_estimate(node->ioss_RelationDesc,
 													  node->ioss_NumScanKeys,
 													  node->ioss_NumOrderByKeys,
-													  estate->es_snapshot);
+													  estate->es_snapshot,
+													  instrument, parallel_aware,
+													  pcxt->nworkers);
 	shm_toc_estimate_chunk(&pcxt->estimator, node->ioss_PscanLen);
 	shm_toc_estimate_keys(&pcxt->estimator, 1);
 }
@@ -728,16 +760,33 @@ ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node,
 {
 	EState	   *estate = node->ss.ps.state;
 	ParallelIndexScanDesc piscan;
+	bool		instrument = node->ss.ps.instrument != NULL;
+	bool		parallel_aware = node->ss.ps.plan->parallel_aware;
+
+	if (!instrument && !parallel_aware)
+	{
+		/* No DSM required by the scan */
+		return;
+	}
 
 	piscan = shm_toc_allocate(pcxt->toc, node->ioss_PscanLen);
 	index_parallelscan_initialize(node->ss.ss_currentRelation,
 								  node->ioss_RelationDesc,
 								  estate->es_snapshot,
-								  piscan);
+								  instrument, parallel_aware, pcxt->nworkers,
+								  &node->ioss_SharedInfo, piscan);
 	shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, piscan);
+
+	if (!parallel_aware)
+	{
+		/* Only here to initialize SharedInfo in DSM */
+		return;
+	}
+
 	node->ioss_ScanDesc =
 		index_beginscan_parallel(node->ss.ss_currentRelation,
 								 node->ioss_RelationDesc,
+								 &node->ioss_Instrument,
 								 node->ioss_NumScanKeys,
 								 node->ioss_NumOrderByKeys,
 								 piscan);
@@ -764,6 +813,7 @@ void
 ExecIndexOnlyScanReInitializeDSM(IndexOnlyScanState *node,
 								 ParallelContext *pcxt)
 {
+	Assert(node->ss.ps.plan->parallel_aware);
 	index_parallelrescan(node->ioss_ScanDesc);
 }
 
@@ -778,11 +828,31 @@ ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node,
 								  ParallelWorkerContext *pwcxt)
 {
 	ParallelIndexScanDesc piscan;
+	bool		instrument = node->ss.ps.instrument != NULL;
+	bool		parallel_aware = node->ss.ps.plan->parallel_aware;
+
+	if (!instrument && !parallel_aware)
+	{
+		/* No DSM required by the scan */
+		return;
+	}
 
 	piscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false);
+
+	if (instrument)
+		node->ioss_SharedInfo = (SharedIndexScanInstrumentation *)
+			OffsetToPointer(piscan, piscan->ps_offset_ins);
+
+	if (!parallel_aware)
+	{
+		/* Only here to set up worker node's SharedInfo */
+		return;
+	}
+
 	node->ioss_ScanDesc =
 		index_beginscan_parallel(node->ss.ss_currentRelation,
 								 node->ioss_RelationDesc,
+								 &node->ioss_Instrument,
 								 node->ioss_NumScanKeys,
 								 node->ioss_NumOrderByKeys,
 								 piscan);
@@ -797,3 +867,25 @@ ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node,
 					 node->ioss_ScanKeys, node->ioss_NumScanKeys,
 					 node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
 }
+
+/* ----------------------------------------------------------------
+ *		ExecIndexOnlyScanRetrieveInstrumentation
+ *
+ *		Transfer index-only scan statistics from DSM to private memory.
+ * ----------------------------------------------------------------
+ */
+void
+ExecIndexOnlyScanRetrieveInstrumentation(IndexOnlyScanState *node)
+{
+	SharedIndexScanInstrumentation *SharedInfo = node->ioss_SharedInfo;
+	size_t		size;
+
+	if (SharedInfo == NULL)
+		return;
+
+	/* Create a copy of SharedInfo in backend-local memory */
+	size = offsetof(SharedIndexScanInstrumentation, winstrument) +
+		SharedInfo->num_workers * sizeof(IndexScanInstrumentation);
+	node->ioss_SharedInfo = palloc(size);
+	memcpy(node->ioss_SharedInfo, SharedInfo, size);
+}