check_attnotnull.diff

diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index a127239d30..c12aa15fc9 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -73,7 +73,7 @@ static bool is_innerrel_unique_for(PlannerInfo *root,
 								   List *restrictlist,
 								   List **extra_clauses);
 static Bitmapset *replace_relid(Relids relids, int oldId, int newId);
-static void replace_varno(Node *node, int from, int to);
+static void replace_varno(PlannerInfo *root, Node *node, int from, int to);
 
 
 /*
@@ -388,7 +388,7 @@ remove_rel_from_query_common(PlannerInfo *root, RelOptInfo *rel,
 		}
 
 		/* Update lateral references. */
-		replace_varno((Node *) otherrel->lateral_vars, relid, subst);
+		replace_varno(root, (Node *) otherrel->lateral_vars, relid, subst);
 	}
 
 	/*
@@ -425,7 +425,7 @@ remove_rel_from_query_common(PlannerInfo *root, RelOptInfo *rel,
 		sjinf->commute_below_l = replace_relid(sjinf->commute_below_l, ojrelid, subst);
 		sjinf->commute_below_r = replace_relid(sjinf->commute_below_r, ojrelid, subst);
 
-		replace_varno((Node *) sjinf->semi_rhs_exprs, relid, subst);
+		replace_varno(root, (Node *) sjinf->semi_rhs_exprs, relid, subst);
 	}
 
 	/*
@@ -1399,6 +1399,7 @@ is_innerrel_unique_for(PlannerInfo *root,
 
 typedef struct ReplaceVarnoContext
 {
+	PlannerInfo *root;
 	int	from;
 	int	to;
 } ReplaceVarnoContext;
@@ -1420,6 +1421,11 @@ replace_varno_walker(Node *node, ReplaceVarnoContext *ctx)
 		}
 		return false;
 	}
+
+	/*
+	 * Expression walker doesn't know about RestrictInfo node. Do recursive pass
+	 * into the clauses manually.
+	 */
 	if (IsA(node, RestrictInfo))
 	{
 		RestrictInfo   *rinfo = (RestrictInfo *) node;
@@ -1429,20 +1435,26 @@ replace_varno_walker(Node *node, ReplaceVarnoContext *ctx)
 
 		if (bms_is_member(ctx->from, rinfo->clause_relids))
 		{
-			replace_varno((Node *) rinfo->clause, ctx->from, ctx->to);
-			replace_varno((Node *) rinfo->orclause, ctx->from, ctx->to);
-			rinfo->clause_relids = replace_relid(rinfo->clause_relids, ctx->from, ctx->to);
-			rinfo->left_relids = replace_relid(rinfo->left_relids, ctx->from, ctx->to);
-			rinfo->right_relids = replace_relid(rinfo->right_relids, ctx->from, ctx->to);
+			replace_varno(ctx->root, (Node *) rinfo->clause, ctx->from, ctx->to);
+			replace_varno(ctx->root, (Node *) rinfo->orclause, ctx->from, ctx->to);
+			rinfo->clause_relids =
+						replace_relid(rinfo->clause_relids, ctx->from, ctx->to);
+			rinfo->left_relids =
+						replace_relid(rinfo->left_relids, ctx->from, ctx->to);
+			rinfo->right_relids =
+						replace_relid(rinfo->right_relids, ctx->from, ctx->to);
 		}
 
 		if (is_req_equal)
 			rinfo->required_relids = rinfo->clause_relids;
 		else
-			rinfo->required_relids = replace_relid(rinfo->required_relids, ctx->from, ctx->to);
+			rinfo->required_relids =
+					replace_relid(rinfo->required_relids, ctx->from, ctx->to);
 
-		rinfo->outer_relids = replace_relid(rinfo->outer_relids, ctx->from, ctx->to);
-		rinfo->incompatible_relids = replace_relid(rinfo->incompatible_relids, ctx->from, ctx->to);
+		rinfo->outer_relids =
+						replace_relid(rinfo->outer_relids, ctx->from, ctx->to);
+		rinfo->incompatible_relids =
+				replace_relid(rinfo->incompatible_relids, ctx->from, ctx->to);
 
 		if (rinfo->mergeopfamilies &&
 			bms_get_singleton_member(rinfo->clause_relids, &relid) &&
@@ -1456,13 +1468,31 @@ replace_varno_walker(Node *node, ReplaceVarnoContext *ctx)
 
 			if (leftOp != NULL && equal(leftOp, rightOp))
 			{
-				NullTest   *ntest = makeNode(NullTest);
+				Oid			reloid = 0;
+				AttrNumber	attnum;
+
+				if (IsA(leftOp, Var))
+				{
+					Var *var = (Var *) leftOp;
+					reloid = ctx->root->simple_rte_array[var->varno]->relid;
+					attnum = var->varattno;
+				}
+
+				if (OidIsValid(reloid) && get_attnotnull(reloid, attnum))
+				{
+					rinfo->clause = (Expr *) makeBoolConst(true, false);
+				}
+				else
+				{
+					NullTest   *ntest = makeNode(NullTest);
+
+					ntest->arg = leftOp;
+					ntest->nulltesttype = IS_NOT_NULL;
+					ntest->argisrow = false;
+					ntest->location = -1;
+					rinfo->clause = (Expr *) ntest;
+				}
 
-				ntest->arg = leftOp;
-				ntest->nulltesttype = IS_NOT_NULL;
-				ntest->argisrow = false;
-				ntest->location = -1;
-				rinfo->clause = (Expr *) ntest;
 				rinfo->mergeopfamilies = NIL;
 			}
 			Assert(rinfo->orclause == NULL);
@@ -1477,13 +1507,14 @@ replace_varno_walker(Node *node, ReplaceVarnoContext *ctx)
  * Replace each occurence of removing relid with the keeping one
  */
 static void
-replace_varno(Node *node, int from , int to)
+replace_varno(PlannerInfo *root, Node *node, int from , int to)
 {
 	ReplaceVarnoContext ctx;
 
 	if (to <= 0)
 		return;
 
+	ctx.root = root;
 	ctx.from = from;
 	ctx.to = to;
 	replace_varno_walker(node, &ctx);
@@ -1531,7 +1562,7 @@ replace_relid(Relids relids, int oldId, int newId)
  * delete them.
  */
 static void
-update_eclass(EquivalenceClass *ec, int from, int to)
+update_eclass(PlannerInfo *root, EquivalenceClass *ec, int from, int to)
 {
 	List	   *new_members = NIL;
 	List	   *new_sources = NIL;
@@ -1553,7 +1584,7 @@ update_eclass(EquivalenceClass *ec, int from, int to)
 		em->em_jdomain->jd_relids = replace_relid(em->em_jdomain->jd_relids, from, to);
 
 		/* We only process inner joins */
-		replace_varno((Node *) em->em_expr, from, to);
+		replace_varno(root, (Node *) em->em_expr, from, to);
 
 		foreach(lc1, new_members)
 		{
@@ -1591,7 +1622,7 @@ update_eclass(EquivalenceClass *ec, int from, int to)
 			continue;
 		}
 
-		replace_varno((Node *) rinfo, from, to);
+		replace_varno(root, (Node *) rinfo, from, to);
 
 		/*
 		 * After switching the clause to the remaining relation, check it for
@@ -1685,7 +1716,7 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 
 		remove_join_clause_from_rels(root, rinfo, rinfo->required_relids);
-		replace_varno((Node *) rinfo, toRemove->relid, toKeep->relid);
+		replace_varno(root, (Node *) rinfo, toRemove->relid, toKeep->relid);
 
 		if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
 			jinfo_candidates = lappend(jinfo_candidates, rinfo);
@@ -1704,7 +1735,7 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 	{
 		RestrictInfo   *rinfo = lfirst_node(RestrictInfo, lc);
 
-		replace_varno((Node *) rinfo, toRemove->relid, toKeep->relid);
+		replace_varno(root, (Node *) rinfo, toRemove->relid, toKeep->relid);
 
 		if (bms_membership(rinfo->required_relids) == BMS_MULTIPLE)
 			jinfo_candidates = lappend(jinfo_candidates, rinfo);
@@ -1792,7 +1823,7 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 	{
 		EquivalenceClass *ec = (EquivalenceClass *) list_nth(root->eq_classes, i);
 
-		update_eclass(ec, toRemove->relid, toKeep->relid);
+		update_eclass(root, ec, toRemove->relid, toKeep->relid);
 		toKeep->eclass_indexes = bms_add_member(toKeep->eclass_indexes, i);
 	}
 
@@ -1804,7 +1835,7 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 	{
 		Node   *node = lfirst(lc);
 
-		replace_varno(node, toRemove->relid, toKeep->relid);
+		replace_varno(root, node, toRemove->relid, toKeep->relid);
 		if (!list_member(toKeep->reltarget->exprs, node))
 			toKeep->reltarget->exprs = lappend(toKeep->reltarget->exprs, node);
 	}
@@ -1851,10 +1882,10 @@ remove_self_join_rel(PlannerInfo *root, PlanRowMark *kmark, PlanRowMark *rmark,
 	/* At last, replace links in the planner info */
 	remove_rel_from_query_common(root, toRemove, toKeep->relid, NULL, NULL);
 	/* replace varno in root targetlist and HAVING clause */
-	replace_varno((Node *) root->processed_tlist,
-				   toRemove->relid, toKeep->relid);
-	replace_varno((Node *) root->processed_groupClause,
-				   toRemove->relid, toKeep->relid);
+	replace_varno(root, (Node *) root->processed_tlist,
+				  toRemove->relid, toKeep->relid);
+	replace_varno(root, (Node *) root->processed_groupClause,
+				  toRemove->relid, toKeep->relid);
 	/* ... and remove the rel from the baserel array */
 	root->simple_rel_array[toRemove->relid] = NULL;
 	pfree(toRemove);
@@ -1914,7 +1945,8 @@ split_selfjoin_quals(PlannerInfo *root, List *joinquals, List **selfjoinquals,
 		 * Quite expensive operation, narrowing the use case. For example, when
 		 * we have cast of the same var to different (but compatible) types.
 		 */
-		replace_varno(rightexpr, bms_singleton_member(rinfo->right_relids),
+		replace_varno(root, rightexpr,
+					  bms_singleton_member(rinfo->right_relids),
 					  bms_singleton_member(rinfo->left_relids));
 
 		if (equal(leftexpr, rightexpr))
@@ -1954,7 +1986,7 @@ match_unique_clauses(PlannerInfo *root, RelOptInfo *outer, List *uclauses,
 			   bms_is_empty(rinfo->right_relids));
 
 		clause = (Expr *) copyObject(rinfo->clause);
-		replace_varno((Node *) clause, relid, outer->relid);
+		replace_varno(root, (Node *) clause, relid, outer->relid);
 
 		iclause = bms_is_empty(rinfo->left_relids) ? get_rightop(clause) :
 													 get_leftop(clause);
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index fc6d267e44..7778ed483f 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -929,6 +929,25 @@ get_attgenerated(Oid relid, AttrNumber attnum)
 	return result;
 }
 
+char
+get_attnotnull(Oid relid, AttrNumber attnum)
+{
+	HeapTuple	tp;
+	Form_pg_attribute att_tup;
+	char		result;
+
+	tp = SearchSysCache2(ATTNUM,
+						 ObjectIdGetDatum(relid),
+						 Int16GetDatum(attnum));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
+			 attnum, relid);
+	att_tup = (Form_pg_attribute) GETSTRUCT(tp);
+	result = att_tup->attnotnull;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*
  * get_atttype
  *
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index f5fdbfe116..02521299a1 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -92,6 +92,7 @@ extern char *get_attname(Oid relid, AttrNumber attnum, bool missing_ok);
 extern AttrNumber get_attnum(Oid relid, const char *attname);
 extern int	get_attstattarget(Oid relid, AttrNumber attnum);
 extern char get_attgenerated(Oid relid, AttrNumber attnum);
+extern char get_attnotnull(Oid relid, AttrNumber attnum);
 extern Oid	get_atttype(Oid relid, AttrNumber attnum);
 extern void get_atttypetypmodcoll(Oid relid, AttrNumber attnum,
 								  Oid *typid, int32 *typmod, Oid *collid);
diff --git a/src/test/regress/expected/equivclass.out b/src/test/regress/expected/equivclass.out
index de71441052..3d5de28354 100644
--- a/src/test/regress/expected/equivclass.out
+++ b/src/test/regress/expected/equivclass.out
@@ -438,15 +438,14 @@ set enable_mergejoin to off;
 explain (costs off)
   select * from ec0 m join ec0 n on m.ff = n.ff
   join ec1 p on m.ff + n.ff = p.f1;
-               QUERY PLAN               
-----------------------------------------
+              QUERY PLAN               
+---------------------------------------
  Nested Loop
    Join Filter: ((n.ff + n.ff) = p.f1)
-   ->  Seq Scan on ec1 p
+   ->  Seq Scan on ec0 n
    ->  Materialize
-         ->  Seq Scan on ec0 n
-               Filter: (ff IS NOT NULL)
-(6 rows)
+         ->  Seq Scan on ec1 p
+(5 rows)
 
 explain (costs off)
   select * from ec0 m join ec0 n on m.ff = n.ff
@@ -455,11 +454,10 @@ explain (costs off)
 ---------------------------------------------------------------
  Nested Loop
    Join Filter: ((p.f1)::bigint = ((n.ff + n.ff))::int8alias1)
-   ->  Seq Scan on ec1 p
+   ->  Seq Scan on ec0 n
    ->  Materialize
-         ->  Seq Scan on ec0 n
-               Filter: (ff IS NOT NULL)
-(6 rows)
+         ->  Seq Scan on ec1 p
+(5 rows)
 
 reset enable_mergejoin;
 -- this could be converted, but isn't at present
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 027c356bcc..10b23944fe 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -6337,14 +6337,14 @@ SELECT * FROM pg_am am WHERE am.amname IN (
     JOIN pg_class c2
     ON c1.oid=c2.oid AND c1.oid < 10
 );
-                             QUERY PLAN                              
----------------------------------------------------------------------
+                           QUERY PLAN                           
+----------------------------------------------------------------
  Nested Loop Semi Join
    Join Filter: (am.amname = c2.relname)
    ->  Seq Scan on pg_am am
    ->  Materialize
          ->  Index Scan using pg_class_oid_index on pg_class c2
-               Index Cond: ((oid < '10'::oid) AND (oid IS NOT NULL))
+               Index Cond: (oid < '10'::oid)
 (6 rows)
 
 --
@@ -6599,14 +6599,14 @@ SELECT COUNT(*) FROM tab_with_flag
 WHERE
 	(is_flag IS NULL OR is_flag = 0)
 	AND id IN (SELECT id FROM tab_with_flag WHERE id IN (2, 3));
-                                    QUERY PLAN                                    
-----------------------------------------------------------------------------------
+                        QUERY PLAN                         
+-----------------------------------------------------------
  Aggregate
    ->  Bitmap Heap Scan on tab_with_flag
-         Recheck Cond: ((id = ANY ('{2,3}'::integer[])) AND (id IS NOT NULL))
+         Recheck Cond: (id = ANY ('{2,3}'::integer[]))
          Filter: ((is_flag IS NULL) OR (is_flag = 0))
          ->  Bitmap Index Scan on tab_with_flag_pkey
-               Index Cond: ((id = ANY ('{2,3}'::integer[])) AND (id IS NOT NULL))
+               Index Cond: (id = ANY ('{2,3}'::integer[]))
 (6 rows)
 
 DROP TABLE tab_with_flag;
@@ -6764,11 +6764,11 @@ reset self_join_search_limit;
 CREATE TABLE emp1 ( id SERIAL PRIMARY KEY NOT NULL, code int);
 explain (verbose, costs off)
 SELECT * FROM emp1 e1, emp1 e2 WHERE e1.id = e2.id AND e2.code <> e1.code;
-                        QUERY PLAN                        
-----------------------------------------------------------
+                QUERY PLAN                
+------------------------------------------
  Seq Scan on public.emp1 e2
    Output: e2.id, e2.code, e2.id, e2.code
-   Filter: ((e2.id IS NOT NULL) AND (e2.code <> e2.code))
+   Filter: (e2.code <> e2.code)
 (3 rows)
 
 -- We can remove the join even if we find the join can't duplicate rows and