From 44a1ea631a34b001b83a66c5415cda58b79e6bbc Mon Sep 17 00:00:00 2001
From: Marco Slot <marco.slot@gmail.com>
Date: Sat, 16 Dec 2017 11:32:01 +0100
Subject: [PATCH] Show distributed subplan ID in EXPLAIN output

---
 .../distributed/planner/multi_explain.c       | 33 ++++++++++---------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/src/backend/distributed/planner/multi_explain.c b/src/backend/distributed/planner/multi_explain.c
index 25523b5eb..cb7906ae9 100644
--- a/src/backend/distributed/planner/multi_explain.c
+++ b/src/backend/distributed/planner/multi_explain.c
@@ -72,7 +72,7 @@ typedef struct RemoteExplainPlan
 
 
 /* Explain functions for distributed queries */
-static void ExplainSubPlans(List *subPlanList, ExplainState *es);
+static void ExplainSubPlans(DistributedPlan *distributedPlan, ExplainState *es);
 static void ExplainJob(Job *job, ExplainState *es);
 static void ExplainMapMergeJob(MapMergeJob *mapMergeJob, ExplainState *es);
 static void ExplainTaskList(List *taskList, ExplainState *es);
@@ -127,7 +127,7 @@ CitusExplainScan(CustomScanState *node, List *ancestors, struct ExplainState *es
 
 	if (distributedPlan->subPlanList != NIL)
 	{
-		ExplainSubPlans(distributedPlan->subPlanList, es);
+		ExplainSubPlans(distributedPlan, es);
 	}
 
 	ExplainJob(distributedPlan->workerJob, es);
@@ -179,20 +179,14 @@ CoordinatorInsertSelectExplainScan(CustomScanState *node, List *ancestors,
  * planning time and set it to 0.
  */
 static void
-ExplainSubPlans(List *subPlanList, ExplainState *es)
+ExplainSubPlans(DistributedPlan *distributedPlan, ExplainState *es)
 {
 	ListCell *subPlanCell = NULL;
+	uint64 planId = distributedPlan->planId;
 
 	ExplainOpenGroup("Subplans", "Subplans", false, es);
 
-	if (es->format == EXPLAIN_FORMAT_TEXT)
-	{
-		appendStringInfoSpaces(es->str, es->indent * 2);
-		appendStringInfo(es->str, "->  Distributed Subplan\n");
-		es->indent += 3;
-	}
-
-	foreach(subPlanCell, subPlanList)
+	foreach(subPlanCell, distributedPlan->subPlanList)
 	{
 		DistributedSubPlan *subPlan = (DistributedSubPlan *) lfirst(subPlanCell);
 		PlannedStmt *plan = subPlan->plan;
@@ -201,6 +195,15 @@ ExplainSubPlans(List *subPlanList, ExplainState *es)
 		char *queryString = NULL;
 		instr_time planduration;
 
+		if (es->format == EXPLAIN_FORMAT_TEXT)
+		{
+			char *resultId = GenerateResultId(planId, subPlan->subPlanId);
+
+			appendStringInfoSpaces(es->str, es->indent * 2);
+			appendStringInfo(es->str, "->  Distributed Subplan %s\n", resultId);
+			es->indent += 3;
+		}
+
 		/* set the planning time to 0 */
 		INSTR_TIME_SET_CURRENT(planduration);
 		INSTR_TIME_SUBTRACT(planduration, planduration);
@@ -210,11 +213,11 @@ ExplainSubPlans(List *subPlanList, ExplainState *es)
 #else
 		ExplainOnePlan(plan, into, es, queryString, params, &planduration);
 #endif
-	}
 
-	if (es->format == EXPLAIN_FORMAT_TEXT)
-	{
-		es->indent -= 3;
+		if (es->format == EXPLAIN_FORMAT_TEXT)
+		{
+			es->indent -= 3;
+		}
 	}
 
 	ExplainCloseGroup("Subplans", "Subplans", false, es);