Bug#48483 crash in get_best_combination()

The crash happens because greedy_serach
can not determine best plan due to
wrong inner table dependences. These
dependences affects join table sorting
which performs before greedy_search starting.
In our case table which has real 'no dependences'
should be put on top of the list but it does not
happen as inner tables have no dependences as well.
The fix is to exclude RAND_TABLE_BIT mask from
condition which checks if table dependences
should be updated.

mysql-test/r/join.result

@@ -913,4 +913,21 @@ ON t4.a = t5.a
 ON t1.a = t3.a;
 a	a	a	a	a	a
 DROP TABLE t1,t2,t3,t4,t5,t6;
+#
+# Bug#48483: crash in get_best_combination()
+#
+CREATE TABLE t1(f1 INT);
+INSERT INTO t1 VALUES (1),(2);
+CREATE VIEW v1 AS SELECT 1 FROM t1 LEFT JOIN t1 AS t2 on 1=1;
+EXPLAIN EXTENDED
+SELECT 1 FROM v1 right join v1 AS v2 ON RAND();
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	
+1	SIMPLE	t2	ALL	NULL	NULL	NULL	NULL	2	
+Warnings:
+Note	1003	select 1 AS `1` from `test`.`t1` left join `test`.`t1` `t2` on((1 = 1)) left join (`test`.`t1` left join `test`.`t1` `t2` on((1 = 1))) on(rand()) where 1
+DROP VIEW v1;
+DROP TABLE t1;
 End of 5.0 tests.

mysql-test/t/join.test

@@ -713,4 +713,16 @@ FROM
 
 DROP TABLE t1,t2,t3,t4,t5,t6;
 
+--echo #
+--echo # Bug#48483: crash in get_best_combination()
+--echo #
+
+CREATE TABLE t1(f1 INT);
+INSERT INTO t1 VALUES (1),(2);
+CREATE VIEW v1 AS SELECT 1 FROM t1 LEFT JOIN t1 AS t2 on 1=1;
+EXPLAIN EXTENDED
+SELECT 1 FROM v1 right join v1 AS v2 ON RAND();
+DROP VIEW v1;
+DROP TABLE t1;
+
 --echo End of 5.0 tests.

sql/sql_select.cc

@@ -4819,6 +4819,11 @@ greedy_search(JOIN      *join,
     if (best_extension_by_limited_search(join, remaining_tables, idx, record_count,
                                          read_time, search_depth, prune_level))
       DBUG_RETURN(TRUE);
+    /*
+      'best_read < DBL_MAX' means that optimizer managed to find
+      some plan and updated 'best_positions' array accordingly.
+    */
+    DBUG_ASSERT(join->best_read < DBL_MAX); 
 
     if (size_remain <= search_depth)
     {
@@ -8431,8 +8436,14 @@ simplify_joins(JOIN *join, List<TABLE_LIST> *join_list, COND *conds, bool top)
           we still make the inner tables dependent on the outer tables.
           It would be enough to set dependency only on one outer table
           for them. Yet this is really a rare case.
-	*/  
-        if (!(prev_table->on_expr->used_tables() & ~prev_used_tables))
+          Note:
+          RAND_TABLE_BIT mask should not be counted as it
+          prevents update of inner table dependences.
+          For example it might happen if RAND() function
+          is used in JOIN ON clause.
+	*/  
+        if (!((prev_table->on_expr->used_tables() & ~RAND_TABLE_BIT) &
+              ~prev_used_tables))
           prev_table->dep_tables|= used_tables;
       }
     }