[SHRDM-762] extract info from foreign join

Author: pyhalov

expected/aqo_fdw.out

@@ -57,11 +57,6 @@ SELECT x FROM frgn;
 (5 rows)
 
 -- Push down base filters. Use verbose mode to see filters.
-EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE))
-SELECT x FROM frgn WHERE x < 10;
-ERROR:  syntax error at or near ")"
-LINE 1: ...LAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE))
-                                                                      ^
 EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE)
 SELECT x FROM frgn WHERE x < 10;
                         QUERY PLAN                         
@@ -75,6 +70,19 @@ SELECT x FROM frgn WHERE x < 10;
  JOINS: 0
 (7 rows)
 
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE)
+SELECT x FROM frgn WHERE x < 10;
+                        QUERY PLAN                         
+-----------------------------------------------------------
+ Foreign Scan on public.frgn (actual rows=1 loops=1)
+   AQO: rows=1, error=0%
+   Output: x
+   Remote SQL: SELECT x FROM public.local WHERE ((x < 10))
+ Using aqo: true
+ AQO mode: LEARN
+ JOINS: 0
+(7 rows)
+
 EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
 SELECT x FROM frgn WHERE x < -10; -- AQO ignores constants
                   QUERY PLAN                  
@@ -143,7 +151,7 @@ SELECT * FROM frgn AS a, frgn AS b WHERE a.x<b.x;
                                                QUERY PLAN                                               
 --------------------------------------------------------------------------------------------------------
  Foreign Scan (actual rows=0 loops=1)
-   AQO not used
+   AQO: rows=1, error=100%
    Output: a.x, b.x
    Relations: (public.frgn a) INNER JOIN (public.frgn b)
    Remote SQL: SELECT r1.x, r2.x FROM (public.local r1 INNER JOIN public.local r2 ON (((r1.x < r2.x))))

path_utils.c

@@ -21,6 +21,7 @@
 #include "aqo.h"
 #include "hash.h"
 
+#include "postgres_fdw.h"
 
 /*
  * Hook on creation of a plan node. We need to store AQO-specific data to
@@ -56,6 +57,31 @@ create_aqo_plan_node()
 	return node;
 }
 
+
+/* Ensure that it's postgres_fdw's foreign server oid */
+static bool
+is_postgres_fdw_server(Oid serverid)
+{
+	ForeignServer *server;
+	ForeignDataWrapper *fdw;
+
+	if (!OidIsValid(serverid))
+		return false;
+
+	server = GetForeignServerExtended(serverid, FSV_MISSING_OK);
+	if (!server)
+		return false;
+
+	fdw = GetForeignDataWrapperExtended(server->fdwid, FDW_MISSING_OK);
+	if (!fdw || !fdw->fdwname)
+		return false;
+
+	if (strcmp(fdw->fdwname, "postgres_fdw") != 0)
+		return false;
+
+	return true;
+}
+
 /*
  * Extract an AQO node from the plan private field.
  * If no one node was found, return pointer to the default value or allocate new
@@ -415,7 +441,8 @@ aqo_create_plan_hook(PlannerInfo *root, Path *src, Plan **dest)
 		return;
 
 	is_join_path = (src->type == T_NestPath || src->type == T_MergePath ||
-					src->type == T_HashPath);
+					src->type == T_HashPath ||
+					(src->type == T_ForeignPath && IS_JOIN_REL(src->parent)));
 
 	node = get_aqo_plan_node(plan, true);
 
@@ -431,8 +458,32 @@ aqo_create_plan_hook(PlannerInfo *root, Path *src, Plan **dest)
 
 	if (is_join_path)
 	{
-		node->clauses = aqo_get_clauses(root, ((JoinPath *) src)->joinrestrictinfo);
-		node->jointype = ((JoinPath *) src)->jointype;
+		if (IsA(src, ForeignPath))
+		{
+			PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) src->parent->fdw_private;
+			List	*restrictclauses = NIL;
+
+			if (!fpinfo)
+				return;
+
+			/* We have to ensure that this is postgres_fdw ForeignPath */
+			if (!is_postgres_fdw_server(src->parent->serverid))
+				return;
+
+			restrictclauses = list_concat(restrictclauses, fpinfo->joinclauses);
+			restrictclauses = list_concat(restrictclauses, fpinfo->remote_conds);
+			restrictclauses = list_concat(restrictclauses, fpinfo->local_conds);
+
+			node->clauses = aqo_get_clauses(root, restrictclauses);
+			node->jointype = fpinfo->jointype;
+
+			list_free(restrictclauses);
+		}
+		else
+		{
+			node->clauses = aqo_get_clauses(root, ((JoinPath *) src)->joinrestrictinfo);
+			node->jointype = ((JoinPath *) src)->jointype;
+		}
 	}
 	else if (IsA(src, AggPath))
 	/* Aggregation node must store grouping clauses. */

sql/aqo_fdw.sql

@@ -47,7 +47,7 @@ EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF)
 SELECT x FROM frgn;
 
 -- Push down base filters. Use verbose mode to see filters.
-EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE))
+EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE)
 SELECT x FROM frgn WHERE x < 10;
 EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF, VERBOSE)
 SELECT x FROM frgn WHERE x < 10;