From da6a7bdcab7d2c594eedf74590920861f1611bcd Mon Sep 17 00:00:00 2001
From: hailanwhu <2013301500074@whu.edu.cn>
Date: Wed, 18 Sep 2019 18:06:15 +1000
Subject: [PATCH] planner: explain a physicalPlan with IndexMerge in "dot"
 format (#12248)

---
 cmd/explaintest/r/explain_indexmerge.result | 33 +++++++++++++++++++++
 cmd/explaintest/t/explain_indexmerge.test   |  1 +
 planner/core/common_plans.go                |  9 ++++++
 3 files changed, 43 insertions(+)

diff --git a/cmd/explaintest/r/explain_indexmerge.result b/cmd/explaintest/r/explain_indexmerge.result
index 314da1ea59439..4498ee0ec9e00 100644
--- a/cmd/explaintest/r/explain_indexmerge.result
+++ b/cmd/explaintest/r/explain_indexmerge.result
@@ -48,3 +48,36 @@ IndexMerge_17	0.00	root
 ├─IndexScan_14	9.00	cop	table:t, index:d, range:[-inf,10), keep order:false
 └─Selection_16	0.00	cop	lt(Column#6, 10), or(lt(Column#2, 10000), lt(Column#3, 10000))
   └─TableScan_15	18.00	cop	table:t, keep order:false
+explain format="dot" select * from t where (a < 50 or b < 50) and f > 100;
+dot contents
+
+digraph IndexMerge_12 {
+subgraph cluster12{
+node [style=filled, color=lightgrey]
+color=black
+label = "root"
+"IndexMerge_12"
+}
+subgraph cluster8{
+node [style=filled, color=lightgrey]
+color=black
+label = "cop"
+"TableScan_8"
+}
+subgraph cluster9{
+node [style=filled, color=lightgrey]
+color=black
+label = "cop"
+"IndexScan_9"
+}
+subgraph cluster11{
+node [style=filled, color=lightgrey]
+color=black
+label = "cop"
+"Selection_11" -> "TableScan_10"
+}
+"IndexMerge_12" -> "TableScan_8"
+"IndexMerge_12" -> "IndexScan_9"
+"IndexMerge_12" -> "Selection_11"
+}
+
diff --git a/cmd/explaintest/t/explain_indexmerge.test b/cmd/explaintest/t/explain_indexmerge.test
index 20a6afb3ef88c..507e7559a0979 100644
--- a/cmd/explaintest/t/explain_indexmerge.test
+++ b/cmd/explaintest/t/explain_indexmerge.test
@@ -12,3 +12,4 @@ explain select * from t where b < 50 or c < 50;
 explain select * from t where b < 50 or c < 5000000;
 explain select * from t where a < 50 or b < 50 or c < 50;
 explain select * from t where (b < 10000 or c < 10000) and (a < 10 or d < 10) and f < 10;
+explain format="dot" select * from t where (a < 50 or b < 50) and f > 100;
diff --git a/planner/core/common_plans.go b/planner/core/common_plans.go
index 1ae6965873688..9a628c7c484c4 100644
--- a/planner/core/common_plans.go
+++ b/planner/core/common_plans.go
@@ -808,6 +808,15 @@ func (e *Explain) prepareTaskDot(p PhysicalPlan, taskTp string, buffer *bytes.Bu
 			pipelines = append(pipelines, fmt.Sprintf("\"%s\" -> \"%s\"\n", copPlan.ExplainID(), copPlan.indexPlan.ExplainID()))
 			copTasks = append(copTasks, copPlan.tablePlan)
 			copTasks = append(copTasks, copPlan.indexPlan)
+		case *PhysicalIndexMergeReader:
+			for i := 0; i < len(copPlan.partialPlans); i++ {
+				pipelines = append(pipelines, fmt.Sprintf("\"%s\" -> \"%s\"\n", copPlan.ExplainID(), copPlan.partialPlans[i].ExplainID()))
+				copTasks = append(copTasks, copPlan.partialPlans[i])
+			}
+			if copPlan.tablePlan != nil {
+				pipelines = append(pipelines, fmt.Sprintf("\"%s\" -> \"%s\"\n", copPlan.ExplainID(), copPlan.tablePlan.ExplainID()))
+				copTasks = append(copTasks, copPlan.tablePlan)
+			}
 		}
 		for _, child := range curPlan.Children() {
 			fmt.Fprintf(buffer, "\"%s\" -> \"%s\"\n", curPlan.ExplainID(), child.ExplainID())