Fixed LP bug #800184.

The function key_and() erroneously called SEL_ARG::increment_use_count()
when SEL_ARG::incr_refs() should had been called. This could lead to
wrong values of use_count for some SEL_ARG trees.

mysql-test/r/range_vs_index_merge.result

@@ -1414,4 +1414,17 @@ a	b	c	d
 0	75	5	3
 SET SESSION optimizer_switch=DEFAULT;
 DROP TABLE t1;
+CREATE TABLE t1 (a int NOT NULL PRIMARY KEY, b int, c int, INDEX idx(c,b));
+INSERT INTO t1 VALUES (19,1,NULL), (20,5,7);
+EXPLAIN
+SELECT * FROM t1
+WHERE t1.a>300 AND t1.c!=0 AND t1.b>=350 AND t1.b<=400 AND
+(t1.c=0 OR t1.a=500);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	PRIMARY,idx	PRIMARY	4	NULL	1	Using where
+SELECT * FROM t1
+WHERE t1.a>300 AND t1.c!=0 AND t1.b>=350 AND t1.b<=400 AND
+(t1.c=0 OR t1.a=500);
+a	b	c
+DROP TABLE t1;
 set session optimizer_switch='index_merge_sort_intersection=default';

mysql-test/r/range_vs_index_merge_innodb.result

@@ -1415,5 +1415,18 @@ a	b	c	d
 0	75	5	3
 SET SESSION optimizer_switch=DEFAULT;
 DROP TABLE t1;
+CREATE TABLE t1 (a int NOT NULL PRIMARY KEY, b int, c int, INDEX idx(c,b));
+INSERT INTO t1 VALUES (19,1,NULL), (20,5,7);
+EXPLAIN
+SELECT * FROM t1
+WHERE t1.a>300 AND t1.c!=0 AND t1.b>=350 AND t1.b<=400 AND
+(t1.c=0 OR t1.a=500);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	PRIMARY,idx	PRIMARY	4	NULL	1	Using where
+SELECT * FROM t1
+WHERE t1.a>300 AND t1.c!=0 AND t1.b>=350 AND t1.b<=400 AND
+(t1.c=0 OR t1.a=500);
+a	b	c
+DROP TABLE t1;
 set session optimizer_switch='index_merge_sort_intersection=default';
 SET SESSION STORAGE_ENGINE=DEFAULT;

mysql-test/t/range_vs_index_merge.test

@@ -1030,9 +1030,8 @@ SELECT * FROM t1,t2,t3
 DROP TABLE t1,t2,t3;
 
 #
-# LP bug #823301: index merge union with prossible index scan  
+# LP bug #823301: index merge sort union with possible index scan  
 #              
-#
 
 CREATE TABLE t1 (
   a int, b int, c int, d int,
@@ -1058,5 +1057,23 @@ SET SESSION optimizer_switch=DEFAULT;
 
 DROP TABLE t1;
 
+#
+# LP bug #800184: possible index merge sort union   
+#              
+
+CREATE TABLE t1 (a int NOT NULL PRIMARY KEY, b int, c int, INDEX idx(c,b));
+INSERT INTO t1 VALUES (19,1,NULL), (20,5,7);
+
+EXPLAIN
+SELECT * FROM t1
+  WHERE t1.a>300 AND t1.c!=0 AND t1.b>=350 AND t1.b<=400 AND
+       (t1.c=0 OR t1.a=500);
+SELECT * FROM t1
+  WHERE t1.a>300 AND t1.c!=0 AND t1.b>=350 AND t1.b<=400 AND
+       (t1.c=0 OR t1.a=500);
+
+DROP TABLE t1;
+
 #the following command must be the last one in the file
 set session optimizer_switch='index_merge_sort_intersection=default';
+

sql/opt_range.cc

@@ -8565,8 +8565,8 @@ key_and(RANGE_OPT_PARAM *param, SEL_ARG *key1, SEL_ARG *key2, uint clone_flag)
       continue;
     SEL_ARG *next=key_and(param, e1->next_key_part, e2->next_key_part,
                           clone_flag);
-    e1->increment_use_count(1);
-    e2->increment_use_count(1);
+    e1->incr_refs();
+    e2->incr_refs();
     if (!next || next->type != SEL_ARG::IMPOSSIBLE)
     {
       SEL_ARG *new_arg= e1->clone_and(e2);