From 2f694f7af3b79a9ec1bb7436bdb9dd4d691acb32 Mon Sep 17 00:00:00 2001
From: Lukas Fittl <lukas@fittl.com>
Date: Wed, 4 May 2016 20:23:05 -0700
Subject: [PATCH] Distributed EXPLAIN: Generate valid JSON output.

This modifies the EXPLAIN output functions to actually generate
valid JSON output when (FORMAT JSON) is being used.

Fixes #494.
---
 .../distributed/planner/multi_explain.c       | 20 +++-
 src/test/regress/expected/multi_explain.out   | 96 ++++++++++---------
 2 files changed, 68 insertions(+), 48 deletions(-)

diff --git a/src/backend/distributed/planner/multi_explain.c b/src/backend/distributed/planner/multi_explain.c
index bb44393df..945bd2d43 100644
--- a/src/backend/distributed/planner/multi_explain.c
+++ b/src/backend/distributed/planner/multi_explain.c
@@ -196,6 +196,10 @@ MultiExplainOneQuery(Query *query, IntoClause *into, ExplainState *es,
 
 		es->indent += 1;
 	}
+	else if (es->format == EXPLAIN_FORMAT_JSON)
+	{
+		ExplainOpenGroup("Distributed Query", NULL, true, es);
+	}
 
 	routerExecutablePlan = RouterExecutablePlan(multiPlan, TaskExecutorType);
 
@@ -245,6 +249,13 @@ MultiExplainOneQuery(Query *query, IntoClause *into, ExplainState *es,
 			appendStringInfo(es->str, "Master Query\n");
 			es->indent += 1;
 		}
+		else if (es->format == EXPLAIN_FORMAT_JSON)
+		{
+			ExplainJSONLineEnding(es);
+			appendStringInfoSpaces(es->str, es->indent * 2);
+			appendStringInfo(es->str, "\"Master Query\":");
+			es->grouping_stack = lcons_int(0, es->grouping_stack);
+		}
 
 		ExplainMasterPlan(masterPlan, into, es, queryString, params, &planDuration);
 
@@ -253,6 +264,11 @@ MultiExplainOneQuery(Query *query, IntoClause *into, ExplainState *es,
 			es->indent -= 1;
 		}
 	}
+
+	if (es->format == EXPLAIN_FORMAT_JSON)
+	{
+		ExplainCloseGroup("Distributed Query", NULL, true, es);
+	}
 }
 
 
@@ -390,7 +406,7 @@ ExplainJob(Job *job, ExplainState *es)
 	List *taskList = job->taskList;
 	int taskCount = list_length(taskList);
 
-	ExplainOpenGroup("Job", NULL, true, es);
+	ExplainOpenGroup("Job", "Job", true, es);
 
 	ExplainPropertyInteger("Task Count", taskCount, es);
 
@@ -424,7 +440,7 @@ ExplainJob(Job *job, ExplainState *es)
 		ExplainCloseGroup("Tasks", "Tasks", false, es);
 	}
 
-	ExplainCloseGroup("Job", NULL, true, es);
+	ExplainCloseGroup("Job", "Job", true, es);
 
 	/* show explain output for depended jobs, if any */
 	foreach(dependedJobCell, dependedJobList)
diff --git a/src/test/regress/expected/multi_explain.out b/src/test/regress/expected/multi_explain.out
index 58fb90d64..78c36c8de 100644
--- a/src/test/regress/expected/multi_explain.out
+++ b/src/test/regress/expected/multi_explain.out
@@ -28,56 +28,59 @@ EXPLAIN (COSTS FALSE, FORMAT JSON)
 	SELECT l_quantity, count(*) count_quantity FROM lineitem
 	GROUP BY l_quantity ORDER BY count_quantity, l_quantity;
 [
-  "Executor": "Real-Time",
   {
-    "Task Count": 6,
-    "Tasks Shown": "One of 6",
-    "Tasks": [
-      {
-        "Node": "host=localhost port=57637 dbname=regression",
-        "Remote Plan": [
-          [
-            {
-              "Plan": {
-                "Node Type": "Aggregate",
-                "Strategy": "Hashed",
-                "Group Key": ["l_quantity"],
-                "Plans": [
-                  {
-                    "Node Type": "Seq Scan",
-                    "Parent Relationship": "Outer",
-                    "Relation Name": "lineitem_102010",
-                    "Alias": "lineitem"
-                  }
-                ]
-              }
-            }
-          ]
-
-        ]
-      }
-    ]
-  },
-  {
-    "Plan": {
-      "Node Type": "Sort",
-      "Sort Key": ["(sum(((sum(intermediate_column_41_1))::bigint)))::bigint", "intermediate_column_41_0"],
-      "Plans": [
+    "Executor": "Real-Time",
+    "Job": {
+      "Task Count": 6,
+      "Tasks Shown": "One of 6",
+      "Tasks": [
         {
-          "Node Type": "Aggregate",
-          "Strategy": "Hashed",
-          "Parent Relationship": "Outer",
-          "Group Key": ["intermediate_column_41_0"],
-          "Plans": [
-            {
-              "Node Type": "Seq Scan",
-              "Parent Relationship": "Outer",
-              "Relation Name": "pg_merge_job_0041",
-              "Alias": "pg_merge_job_0041"
-            }
+          "Node": "host=localhost port=57637 dbname=regression",
+          "Remote Plan": [
+            [
+              {
+                "Plan": {
+                  "Node Type": "Aggregate",
+                  "Strategy": "Hashed",
+                  "Group Key": ["l_quantity"],
+                  "Plans": [
+                    {
+                      "Node Type": "Seq Scan",
+                      "Parent Relationship": "Outer",
+                      "Relation Name": "lineitem_102010",
+                      "Alias": "lineitem"
+                    }
+                  ]
+                }
+              }
+            ]
+
           ]
         }
       ]
+    },
+    "Master Query":
+    {
+      "Plan": {
+        "Node Type": "Sort",
+        "Sort Key": ["(sum(((sum(intermediate_column_41_1))::bigint)))::bigint", "intermediate_column_41_0"],
+        "Plans": [
+          {
+            "Node Type": "Aggregate",
+            "Strategy": "Hashed",
+            "Parent Relationship": "Outer",
+            "Group Key": ["intermediate_column_41_0"],
+            "Plans": [
+              {
+                "Node Type": "Seq Scan",
+                "Parent Relationship": "Outer",
+                "Relation Name": "pg_merge_job_0041",
+                "Alias": "pg_merge_job_0041"
+              }
+            ]
+          }
+        ]
+      }
     }
   }
 ]
@@ -150,7 +153,8 @@ EXPLAIN (COSTS FALSE, FORMAT YAML)
 	SELECT l_quantity, count(*) count_quantity FROM lineitem
 	GROUP BY l_quantity ORDER BY count_quantity, l_quantity;
 Executor: "Real-Time"
-- Task Count: 6
+Job: 
+  Task Count: 6
   Tasks Shown: "One of 6"
   Tasks: 
     - Node: "host=localhost port=57637 dbname=regression"