Bugfix for GROUP BY on expression problem.

Problematic query was: SELECT count(*) FROM pt group by pt.id + 1;

Author: danolivo

contrib/pg_exchange/exchange.c

@@ -197,7 +197,7 @@ EXCHANGE_Init_methods(void)
 	/* Initialize path generator methods */
 	exchange_path_methods.CustomName = EXCHANGEPATHNAME;
 	exchange_path_methods.PlanCustomPath = ExchangePlanCustomPath;
-	exchange_path_methods.ReparameterizeCustomPathByChild	= NULL;
+	exchange_path_methods.ReparameterizeCustomPathByChild = NULL;
 
 	exchange_plan_methods.CustomName = "ExchangePlan";
 	exchange_plan_methods.CreateCustomScanState	= EXCHANGE_Create_state;
@@ -399,7 +399,7 @@ add_exchange_paths(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry
 																EXCH_GATHER);
 		set_exchange_altrel(EXCH_GATHER, (ExchangePath *) path, rel, NULL, NULL,
 																	servers);
-		path = create_distexec_path(root, rel, path, servers);
+		path = (Path *) create_distexec_path(root, rel, path, servers);
 		add_path(rel, path);
 	}
 }
@@ -713,7 +713,6 @@ create_exchange_path(PlannerInfo *root, RelOptInfo *rel, Path *children,
 	pathnode->pathkeys = NIL;
 
 	path->flags = 0;
-	/* Contains only one path */
 	path->custom_paths = lappend(path->custom_paths, children);
 
 	path->custom_private = NIL;
@@ -790,6 +789,7 @@ make_exchange(List *custom_plans, List *tlist)
 {
 	CustomScan	*node = makeNode(CustomScan);
 	Plan		*plan = &node->scan.plan;
+	List *child_tlist;
 
 	plan->startup_cost = 1;
 	plan->total_cost = 1;
@@ -804,9 +804,10 @@ make_exchange(List *custom_plans, List *tlist)
 
 	/* Setup methods and child plan */
 	node->methods = &exchange_plan_methods;
-	node->custom_scan_tlist = tlist;
 	node->scan.scanrelid = 0;
 	node->custom_plans = custom_plans;
+	child_tlist = ((Plan *)linitial(node->custom_plans))->targetlist;
+	node->custom_scan_tlist = child_tlist;
 	node->custom_exprs = NIL;
 	node->custom_private = NIL;
 

contrib/pg_exchange/hooks.c

@@ -226,7 +226,7 @@ create_distributed_join_paths(PlannerInfo *root, RelOptInfo *joinrel,
 							&inn_child->altrel, extra->restrictlist,
 							bms_union(inner_servers, outer_servers));
 			Assert(gather->altrel.part_scheme != NULL);
-			path = create_distexec_path(root, gather->cp.path.parent, (Path *) gather,
+			path = (Path *) create_distexec_path(root, joinrel, (Path *) gather,
 									bms_union(inner_servers, outer_servers));
 			dist_paths = lappend(dist_paths, path);
 			list_free(outerrel->pathlist);

contrib/pg_exchange/nodeDistPlanExec.c

@@ -412,7 +412,7 @@ DistExec_Init_methods(void)
 	/* Initialize path generator methods */
 	distplanexec_path_methods.CustomName = DISTEXECPATHNAME;
 	distplanexec_path_methods.PlanCustomPath = CreateDistExecPlan;
-	distplanexec_path_methods.ReparameterizeCustomPathByChild	= NULL;
+	distplanexec_path_methods.ReparameterizeCustomPathByChild = NULL;
 
 	distplanexec_plan_methods.CustomName 			= "DistExecPlan";
 	distplanexec_plan_methods.CreateCustomScanState	= CreateDistPlanExecState;
@@ -440,6 +440,7 @@ make_distplanexec(List *custom_plans, List *tlist, List *private_data)
 	CustomScan	*node = makeNode(CustomScan);
 	Plan		*plan = &node->scan.plan;
 	ListCell	*lc;
+	List *child_tlist;
 
 	plan->startup_cost = 10;
 	plan->total_cost = 10;
@@ -454,9 +455,11 @@ make_distplanexec(List *custom_plans, List *tlist, List *private_data)
 
 	/* Setup methods and child plan */
 	node->methods = &distplanexec_plan_methods;
-	node->custom_scan_tlist = tlist;
 	node->scan.scanrelid = 0;
 	node->custom_plans = custom_plans;
+
+	child_tlist = ((Plan *)linitial(node->custom_plans))->targetlist;
+	node->custom_scan_tlist = child_tlist;
 	node->custom_exprs = NIL;
 	node->custom_private = NIL;
 
@@ -471,7 +474,7 @@ make_distplanexec(List *custom_plans, List *tlist, List *private_data)
 	return node;
 }
 
-Path *
+CustomPath *
 create_distexec_path(PlannerInfo *root, RelOptInfo *rel, Path *children,
 					 Bitmapset *servers)
 {
@@ -480,27 +483,29 @@ create_distexec_path(PlannerInfo *root, RelOptInfo *rel, Path *children,
 	int member = -1;
 
 	pathnode->pathtype = T_CustomScan;
-	pathnode->parent = rel;
 	pathnode->pathtarget = rel->reltarget;
 	pathnode->param_info = NULL;
+	pathnode->parent = rel;
 
 	pathnode->parallel_aware = false; /* permanently */
 	pathnode->parallel_safe = false; /* permanently */
 	pathnode->parallel_workers = 0; /* permanently */
 	pathnode->pathkeys = NIL;
 
-	pathnode->rows = rel->tuples;
-	pathnode->startup_cost = 10;
-	pathnode->total_cost = 10;
-
 	path->flags = 0;
 	path->custom_paths = lappend(path->custom_paths, children);
+	path->custom_private = NIL;
 
 	while ((member = bms_next_member(servers, member)) >= 0)
 		path->custom_private = lappend_oid(path->custom_private, (Oid) member);
 
 	path->methods = &distplanexec_path_methods;
-	return pathnode;
+
+	pathnode->rows = children->rows;
+	pathnode->startup_cost = 100.;
+	pathnode->total_cost = pathnode->startup_cost;
+
+	return path;
 }
 
 bool

contrib/pg_exchange/nodeDistPlanExec.h

@@ -34,7 +34,7 @@ extern char destsName[10];
 extern Bitmapset *extractForeignServers(CustomPath *path);
 extern void DistExec_Init_methods(void);
 extern CustomScan *make_distplanexec(List *custom_plans, List *tlist, List *private_data);
-extern Path *create_distexec_path(PlannerInfo *root, RelOptInfo *rel,
+extern CustomPath *create_distexec_path(PlannerInfo *root, RelOptInfo *rel,
 								  Path *children, Bitmapset *servers);
 extern bool localize_plan(PlanState *node, lcontext *context);
 extern void FSExtractServerName(Oid fsid, char **host, int *port);

contrib/pg_execplan/tests/test.sql

@@ -8,3 +8,5 @@ SELECT count(*) FROM pt,rt WHERE pt.id=rt.id;
 SELECT count(*) FROM pt,rt,st WHERE pt.id=rt.id and rt.id=st.id;
 SELECT count(*) FROM pt,rt,st WHERE pt.id=rt.id and rt.id=st.payload;
 SELECT count(*) FROM pt,rt,st WHERE pt.id=rt.payload and rt.id=st.payload;
+SELECT count(*) FROM pt group by pt.id;
+SELECT count(*) FROM pt group by pt.id + 1;