Merge fix for BUG##806524

mysql-test/r/derived.result

@@ -477,3 +477,24 @@ WHERE t.f2='s' AND t.f2 LIKE '%a%' OR t.f1<>0 ORDER BY t.f2;
 f1
 8
 DROP TABLE t1, t2;
+#
+# BUG##806524: Assertion `join->best_read < 1.7976931348623157e+308 with table_elimination=on and derived_merge=on 
+# 
+CREATE TABLE t1 ( f4 int) ;
+CREATE TABLE t2 ( f4 int) ;
+CREATE TABLE t3 ( f1 int NOT NULL , PRIMARY KEY (f1)) ;
+CREATE TABLE t4 ( f2 int, f4 int) ;
+SELECT *
+FROM ( SELECT * FROM t1 ) AS alias1
+RIGHT JOIN (
+t2 AS alias2
+LEFT JOIN (
+SELECT t4.*
+FROM ( SELECT * FROM t3 ) AS SQ1_alias1
+RIGHT JOIN t4
+ON t4.f2 = SQ1_alias1.f1
+) AS alias3
+ON alias3.f4 != 0
+) ON alias3.f4 != 0;
+f4	f4	f2	f4
+drop table t1,t2,t3,t4;

mysql-test/t/derived.test

@@ -385,3 +385,27 @@ SELECT DISTINCT t.f1 FROM (SELECT * FROM t1) AS t, t2
   WHERE t.f2='s' AND t.f2 LIKE '%a%' OR t.f1<>0 ORDER BY t.f2;
 
 DROP TABLE t1, t2;
+
+--echo #
+--echo # BUG##806524: Assertion `join->best_read < 1.7976931348623157e+308 with table_elimination=on and derived_merge=on 
+--echo # 
+CREATE TABLE t1 ( f4 int) ;
+CREATE TABLE t2 ( f4 int) ;
+CREATE TABLE t3 ( f1 int NOT NULL , PRIMARY KEY (f1)) ;
+CREATE TABLE t4 ( f2 int, f4 int) ;
+
+SELECT *
+FROM ( SELECT * FROM t1 ) AS alias1
+RIGHT JOIN (
+        t2 AS alias2
+        LEFT JOIN (
+                SELECT t4.*
+                FROM ( SELECT * FROM t3 ) AS SQ1_alias1
+                RIGHT JOIN t4
+                ON t4.f2 = SQ1_alias1.f1
+        ) AS alias3
+        ON alias3.f4 != 0
+) ON alias3.f4 != 0;
+
+drop table t1,t2,t3,t4;
+

sql/sql_select.cc

@@ -12003,8 +12003,8 @@ static uint reset_nj_counters(JOIN *join, List<TABLE_LIST> *join_list)
       if (!nested_join->n_tables)
         is_eliminated_nest= TRUE;
     }
-    if ((!table->table && !is_eliminated_nest) || 
-        (table->table && (table->table->map & ~join->eliminated_tables)))
+    if ((table->nested_join && !is_eliminated_nest) || 
+        (!table->nested_join && (table->table->map & ~join->eliminated_tables)))
       n++;
   }
   DBUG_RETURN(n);