MDEV-17518: Range optimization doesn't use ON expressions from nested outer joins

Part#2: take into account that join nest that we are marking as constant
might already have constant tables in it. Don't count these tables twice.

mysql-test/main/join_outer.result

@@ -2564,4 +2564,19 @@ drop table t1,t2,t3;
 set optimizer_use_condition_selectivity= @tmp1;
 set use_stat_tables= @tmp2;
 set histogram_size= @tmp3;
+# Another test
+CREATE TABLE t1 (i1 int) ;
+CREATE TABLE t2 (pk int NOT NULL PRIMARY KEY) ;
+CREATE TABLE t3 (pk int NOT NULL, i1 int, PRIMARY KEY (pk)) ;
+INSERT INTO t3 VALUES (2, NULL);
+CREATE TABLE t4 (pk int NOT NULL, i1 int, PRIMARY KEY (pk), KEY i1 (i1)) ;
+CREATE VIEW v4 AS SELECT * FROM t4;
+SELECT 1
+FROM t3 RIGHT JOIN t1 ON t3.i1 = t1.i1
+LEFT JOIN v4
+RIGHT JOIN t2 ON v4.i1 = t2.pk ON t1.i1 = t2.pk
+WHERE t3.pk IN (2);
+1
+drop view v4;
+drop table t1,t2,t3,t4;
 SET optimizer_switch=@save_optimizer_switch;

mysql-test/main/join_outer.test

@@ -2084,5 +2084,22 @@ set optimizer_use_condition_selectivity= @tmp1;
 set use_stat_tables= @tmp2;
 set histogram_size= @tmp3;
 
+--echo # Another test
+CREATE TABLE t1 (i1 int) ;
+CREATE TABLE t2 (pk int NOT NULL PRIMARY KEY) ;
+CREATE TABLE t3 (pk int NOT NULL, i1 int, PRIMARY KEY (pk)) ;
+INSERT INTO t3 VALUES (2, NULL);
+
+CREATE TABLE t4 (pk int NOT NULL, i1 int, PRIMARY KEY (pk), KEY i1 (i1)) ;
+CREATE VIEW v4 AS SELECT * FROM t4;
+
+SELECT 1
+FROM t3 RIGHT JOIN t1 ON t3.i1 = t1.i1
+  LEFT JOIN v4
+  RIGHT JOIN t2 ON v4.i1 = t2.pk ON t1.i1 = t2.pk
+WHERE t3.pk IN (2);
+
+drop view v4;
+drop table t1,t2,t3,t4;
 
 SET optimizer_switch=@save_optimizer_switch;

mysql-test/main/join_outer_jcl6.result

@@ -2575,6 +2575,21 @@ drop table t1,t2,t3;
 set optimizer_use_condition_selectivity= @tmp1;
 set use_stat_tables= @tmp2;
 set histogram_size= @tmp3;
+# Another test
+CREATE TABLE t1 (i1 int) ;
+CREATE TABLE t2 (pk int NOT NULL PRIMARY KEY) ;
+CREATE TABLE t3 (pk int NOT NULL, i1 int, PRIMARY KEY (pk)) ;
+INSERT INTO t3 VALUES (2, NULL);
+CREATE TABLE t4 (pk int NOT NULL, i1 int, PRIMARY KEY (pk), KEY i1 (i1)) ;
+CREATE VIEW v4 AS SELECT * FROM t4;
+SELECT 1
+FROM t3 RIGHT JOIN t1 ON t3.i1 = t1.i1
+LEFT JOIN v4
+RIGHT JOIN t2 ON v4.i1 = t2.pk ON t1.i1 = t2.pk
+WHERE t3.pk IN (2);
+1
+drop view v4;
+drop table t1,t2,t3,t4;
 SET optimizer_switch=@save_optimizer_switch;
 set join_cache_level=default;
 show variables like 'join_cache_level';

sql/sql_select.cc

@@ -4316,14 +4316,17 @@ void mark_join_nest_as_const(JOIN *join,
     }
     JOIN_TAB *tab= tbl->table->reginfo.join_tab;
 
-    tab->type= JT_CONST;
-    tab->info= ET_IMPOSSIBLE_ON_CONDITION;
-    tab->table->const_table= 1;
-
-    join->const_table_map|= tab->table->map;
-    *found_const_table_map|= tab->table->map;
-    set_position(join,(*const_count)++,tab,(KEYUSE*) 0);
-    mark_as_null_row(tab->table);		// All fields are NULL
+    if (!(join->const_table_map & tab->table->map))
+    {
+      tab->type= JT_CONST;
+      tab->info= ET_IMPOSSIBLE_ON_CONDITION;
+      tab->table->const_table= 1;
+
+      join->const_table_map|= tab->table->map;
+      *found_const_table_map|= tab->table->map;
+      set_position(join,(*const_count)++,tab,(KEYUSE*) 0);
+      mark_as_null_row(tab->table);		// All fields are NULL
+    }
   }
 }