INSERT/SELECT: show method in EXPLAIN output

src/backend/distributed/executor/citus_custom_scan.c

@@ -62,7 +62,7 @@ CustomScanMethods TaskTrackerCustomScanMethods = {
 };
 
 CustomScanMethods CoordinatorInsertSelectCustomScanMethods = {
-	"Citus INSERT ... SELECT via coordinator",
+	"Citus INSERT ... SELECT",
 	CoordinatorInsertSelectCreateScan
 };
 

src/backend/distributed/executor/insert_select_executor.c

@@ -69,13 +69,11 @@ static List * BuildColumnNameListFromTargetList(Oid targetRelationId,
 static int PartitionColumnIndexFromColumnList(Oid relationId, List *columnNameList);
 static List * AddInsertSelectCasts(List *insertTargetList, List *selectTargetList,
 								   Oid targetRelationId);
-static bool IsSupportedRedistributionTarget(Oid targetRelationId);
 static List * RedistributedInsertSelectTaskList(Query *insertSelectQuery,
 												DistTableCacheEntry *targetRelation,
 												List **redistributedResults,
 												bool useBinaryFormat);
 static int PartitionColumnIndex(List *insertTargetList, Var *partitionColumn);
-static bool IsRedistributablePlan(Plan *selectPlan);
 static Expr * CastExpr(Expr *expr, Oid sourceType, Oid targetType, Oid targetCollation,
 					   int targetTypeMod);
 static void WrapTaskListForProjection(List *taskList, List *projectedTargetEntries);
@@ -873,7 +871,7 @@ CastExpr(Expr *expr, Oid sourceType, Oid targetType, Oid targetCollation,
  * IsSupportedRedistributionTarget determines whether re-partitioning into the
  * given target relation is supported.
  */
-static bool
+bool
 IsSupportedRedistributionTarget(Oid targetRelationId)
 {
 	DistTableCacheEntry *tableEntry = DistributedTableCacheEntry(targetRelationId);
@@ -966,7 +964,7 @@ RedistributedInsertSelectTaskList(Query *insertSelectQuery,
 		ereport(DEBUG2, (errmsg("distributed statement: %s", queryString->data)));
 
 		LockShardDistributionMetadata(shardId, ShareLock);
-		List *insertShardPlacementList = FinalizedShardPlacementList(shardId);
+		List *insertShardPlacementList = ActiveShardPlacementList(shardId);
 
 		RelationShard *relationShard = CitusMakeNode(RelationShard);
 		relationShard->relationId = targetShardInterval->relationId;
@@ -1015,7 +1013,7 @@ PartitionColumnIndex(List *insertTargetList, Var *partitionColumn)
 /*
  * IsRedistributablePlan returns true if the given plan is a redistrituable plan.
  */
-static bool
+bool
 IsRedistributablePlan(Plan *selectPlan)
 {
 	/* don't redistribute if query is not distributed or requires merge on coordinator */

src/backend/distributed/planner/multi_explain.c

@@ -32,6 +32,7 @@
 #include "distributed/multi_logical_planner.h"
 #include "distributed/multi_master_planner.h"
 #include "distributed/multi_physical_planner.h"
+#include "distributed/multi_router_planner.h"
 #include "distributed/distributed_planner.h"
 #include "distributed/multi_server_executor.h"
 #include "distributed/remote_commands.h"
@@ -139,9 +140,12 @@ CoordinatorInsertSelectExplainScan(CustomScanState *node, List *ancestors,
 	DistributedPlan *distributedPlan = scanState->distributedPlan;
 	Query *insertSelectQuery = distributedPlan->insertSelectQuery;
 	Query *query = BuildSelectForInsertSelect(insertSelectQuery);
+	RangeTblEntry *insertRte = ExtractResultRelationRTE(insertSelectQuery);
+	Oid targetRelationId = insertRte->relid;
 	IntoClause *into = NULL;
 	ParamListInfo params = NULL;
 	char *queryString = NULL;
+	int cursorOptions = CURSOR_OPT_PARALLEL_OK;
 
 	if (es->analyze)
 	{
@@ -150,6 +154,17 @@ CoordinatorInsertSelectExplainScan(CustomScanState *node, List *ancestors,
 							   "... SELECT commands via the coordinator")));
 	}
 
+	PlannedStmt *selectPlan = pg_plan_query(query, cursorOptions, params);
+	if (IsRedistributablePlan(selectPlan->planTree) &&
+		IsSupportedRedistributionTarget(targetRelationId))
+	{
+		ExplainPropertyText("INSERT/SELECT method", "repartition", es);
+	}
+	else
+	{
+		ExplainPropertyText("INSERT/SELECT method", "pull to coordinator", es);
+	}
+
 	ExplainOpenGroup("Select Query", "Select Query", false, es);
 
 	/* explain the inner SELECT query */

src/include/distributed/insert_select_executor.h

@@ -20,6 +20,8 @@
 extern TupleTableSlot * CoordinatorInsertSelectExecScan(CustomScanState *node);
 extern bool ExecutingInsertSelect(void);
 extern Query * BuildSelectForInsertSelect(Query *insertSelectQuery);
+extern bool IsSupportedRedistributionTarget(Oid targetRelationId);
+extern bool IsRedistributablePlan(Plan *selectPlan);
 
 
 #endif /* INSERT_SELECT_EXECUTOR_H */

src/test/regress/expected/insert_select_repartition.out

@@ -275,9 +275,9 @@ SET citus.log_remote_commands TO true; SET client_min_messages TO DEBUG;
    CREATE TABLE results AS SELECT max(-a), array_agg(mapped_key) FROM source_table GROUP BY a;
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  building index "pg_toast_xxxxx_index" on table "pg_toast_xxxxx" serially
-LOG:  issuing SELECT max((OPERATOR(pg_catalog.-) a)) AS max, array_agg(mapped_key) AS array_agg, a AS worker_column_3 FROM insert_select_repartition.source_table_4213601 source_table WHERE true GROUP BY a
+NOTICE:  issuing SELECT max((OPERATOR(pg_catalog.-) a)) AS max, array_agg(mapped_key) AS array_agg, a AS worker_column_3 FROM insert_select_repartition.source_table_4213601 source_table WHERE true GROUP BY a
-LOG:  issuing SELECT max((OPERATOR(pg_catalog.-) a)) AS max, array_agg(mapped_key) AS array_agg, a AS worker_column_3 FROM insert_select_repartition.source_table_4213602 source_table WHERE true GROUP BY a
+NOTICE:  issuing SELECT max((OPERATOR(pg_catalog.-) a)) AS max, array_agg(mapped_key) AS array_agg, a AS worker_column_3 FROM insert_select_repartition.source_table_4213602 source_table WHERE true GROUP BY a
-LOG:  issuing SELECT max((OPERATOR(pg_catalog.-) a)) AS max, array_agg(mapped_key) AS array_agg, a AS worker_column_3 FROM insert_select_repartition.source_table_4213603 source_table WHERE true GROUP BY a
+NOTICE:  issuing SELECT max((OPERATOR(pg_catalog.-) a)) AS max, array_agg(mapped_key) AS array_agg, a AS worker_column_3 FROM insert_select_repartition.source_table_4213603 source_table WHERE true GROUP BY a
 RESET citus.log_remote_commands; RESET client_min_messages;
 DROP TABLE results;
 -- now verify that we don't write the extra columns to the intermediate result files and
@@ -555,6 +555,24 @@ SELECT * FROM target_table ORDER BY a;
  5 | 400
 (6 rows)
 
+--
+-- EXPLAIN output should specify repartitioned INSERT/SELECT
+--
+EXPLAIN INSERT INTO target_table SELECT a, max(b) FROM source_table GROUP BY a;
+                                                 QUERY PLAN
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)  (cost=0.00..0.00 rows=0 width=0)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)  (cost=0.00..0.00 rows=0 width=0)
+         Task Count: 4
+         Tasks Shown: One of 4
+         ->  Task
+               Node: host=localhost port=xxxxx dbname=regression
+               ->  HashAggregate  (cost=43.90..45.90 rows=200 width=8)
+                     Group Key: a
+                     ->  Seq Scan on source_table_4213606 source_table  (cost=0.00..32.60 rows=2260 width=8)
+(10 rows)
+
 DROP TABLE source_table, target_table;
 SET client_min_messages TO WARNING;
 DROP SCHEMA insert_select_repartition CASCADE;

src/test/regress/expected/multi_explain.out

@@ -1188,7 +1188,8 @@ ROLLBACK;
 EXPLAIN (COSTS OFF)
 INSERT INTO lineitem_hash_part
 SELECT o_orderkey FROM orders_hash_part LIMIT 3;
-Custom Scan (Citus INSERT ... SELECT via coordinator)
+Custom Scan (Citus INSERT ... SELECT)
+  INSERT/SELECT method: pull to coordinator
   ->  Limit
         ->  Custom Scan (Citus Adaptive)
               Task Count: 4
@@ -1205,7 +1206,8 @@ t
 EXPLAIN (COSTS OFF)
 INSERT INTO lineitem_hash_part (l_orderkey, l_quantity)
 SELECT o_orderkey, 5 FROM orders_hash_part LIMIT 3;
-Custom Scan (Citus INSERT ... SELECT via coordinator)
+Custom Scan (Citus INSERT ... SELECT)
+  INSERT/SELECT method: pull to coordinator
   ->  Limit
         ->  Custom Scan (Citus Adaptive)
               Task Count: 4
@@ -1217,7 +1219,8 @@ Custom Scan (Citus INSERT ... SELECT via coordinator)
 EXPLAIN (COSTS OFF)
 INSERT INTO lineitem_hash_part (l_orderkey)
 SELECT s FROM generate_series(1,5) s;
-Custom Scan (Citus INSERT ... SELECT via coordinator)
+Custom Scan (Citus INSERT ... SELECT)
+  INSERT/SELECT method: pull to coordinator
   ->  Function Scan on generate_series s
 -- WHERE EXISTS forces pg12 to materialize cte
 EXPLAIN (COSTS OFF)
@@ -1225,7 +1228,8 @@ WITH cte1 AS (SELECT s FROM generate_series(1,10) s)
 INSERT INTO lineitem_hash_part
 WITH cte1 AS (SELECT * FROM cte1 WHERE EXISTS (SELECT * FROM cte1) LIMIT 5)
 SELECT s FROM cte1 WHERE EXISTS (SELECT * FROM cte1);
-Custom Scan (Citus INSERT ... SELECT via coordinator)
+Custom Scan (Citus INSERT ... SELECT)
+  INSERT/SELECT method: pull to coordinator
   ->  Result
         One-Time Filter: $3
         CTE cte1
@@ -1244,7 +1248,8 @@ EXPLAIN (COSTS OFF)
 INSERT INTO lineitem_hash_part
 ( SELECT s FROM generate_series(1,5) s) UNION
 ( SELECT s FROM generate_series(5,10) s);
-Custom Scan (Citus INSERT ... SELECT via coordinator)
+Custom Scan (Citus INSERT ... SELECT)
+  INSERT/SELECT method: pull to coordinator
   ->  HashAggregate
         Group Key: s.s
         ->  Append

src/test/regress/sql/insert_select_repartition.sql

@@ -265,6 +265,13 @@ RESET client_min_messages;
 
 SELECT * FROM target_table ORDER BY a;
 
+--
+-- EXPLAIN output should specify repartitioned INSERT/SELECT
+--
+
+EXPLAIN INSERT INTO target_table SELECT a, max(b) FROM source_table GROUP BY a;
+
+
 DROP TABLE source_table, target_table;
 
 SET client_min_messages TO WARNING;