Fixed bug #14292: performance degradation for a benchmark query.

This performance degradation was due to the fact that some
cost evaluation code added into 4.1 in the function find_best was
not merged into the code of the function best_access_path added
together with other code for greedy optimizer.
Added a parameter to the function print_plan. The parameter contains
accumulated cost for a given partial join.
 
The patch does not include a special test case since this performance
degradation is hard to reproduse with a simple example.

TODO: make the function find_best use the function best_access_path
in order to remove duplication of code which might result in incomplete
merges in the future.

mysql-test/r/delete.result

@@ -186,8 +186,8 @@ a	b	a	b	a	b
 explain select * from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	
-1	SIMPLE	t2	index	PRIMARY	PRIMARY	8	NULL	3	Using where; Using index
-1	SIMPLE	t3	index	PRIMARY	PRIMARY	8	NULL	3	Using where; Using index
+1	SIMPLE	t2	ref	PRIMARY	PRIMARY	4	test.t1.a	1	Using index
+1	SIMPLE	t3	eq_ref	PRIMARY	PRIMARY	8	test.t2.b,test.t1.b	1	Using index
 delete t2.*,t3.* from t1,t2,t3 where t1.a=t2.a AND t2.b=t3.a and t1.b=t3.b;
 select * from t3;
 a	b

mysql-test/r/subselect.result

@@ -1354,10 +1354,10 @@ a
 explain extended select * from t2 where t2.a in (select t1.a from t1,t3 where t1.b=t3.a);
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	PRIMARY	t2	index	NULL	a	5	NULL	4	Using where; Using index
-2	DEPENDENT SUBQUERY	t3	index	a	a	5	NULL	3	Using index
-2	DEPENDENT SUBQUERY	t1	ref	a	a	10	func,test.t3.a	1167	Using where; Using index
+2	DEPENDENT SUBQUERY	t1	ref	a	a	5	func	1001	Using where; Using index
+2	DEPENDENT SUBQUERY	t3	index	a	a	5	NULL	3	Using where; Using index
 Warnings:
-Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t1`.`b` = `test`.`t3`.`a`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))
+Note	1003	select `test`.`t2`.`a` AS `a` from `test`.`t2` where <in_optimizer>(`test`.`t2`.`a`,<exists>(select 1 AS `Not_used` from `test`.`t1` join `test`.`t3` where ((`test`.`t3`.`a` = `test`.`t1`.`b`) and (<cache>(`test`.`t2`.`a`) = `test`.`t1`.`a`))))
 insert into t1 values (3,31);
 select * from t2 where t2.a in (select a from t1 where t1.b <> 30);
 a

sql/mysql_priv.h

@@ -1066,8 +1066,8 @@ pthread_handler_t handle_manager(void *arg);
 void print_where(COND *cond,const char *info);
 void print_cached_tables(void);
 void TEST_filesort(SORT_FIELD *sortorder,uint s_length);
-void print_plan(JOIN* join, double read_time, double record_count,
-                uint idx, const char *info);
+void print_plan(JOIN* join,uint idx, double record_count, double read_time,
+                double current_read_time, const char *info);
 #endif
 void mysql_print_status();
 /* key.cc */

sql/sql_test.cc

@@ -230,8 +230,8 @@ TEST_join(JOIN *join)
 */
 
 void
-print_plan(JOIN* join, double read_time, double record_count,
-           uint idx, const char *info)
+print_plan(JOIN* join, uint idx, double record_count, double read_time,
+           double current_read_time, const char *info)
 {
   uint i;
   POSITION pos;
@@ -245,13 +245,15 @@ print_plan(JOIN* join, double read_time, double record_count,
   DBUG_LOCK_FILE;
   if (join->best_read == DBL_MAX)
   {
-    fprintf(DBUG_FILE,"%s; idx:%u, best: DBL_MAX, current:%g\n",
-            info, idx, read_time);
+    fprintf(DBUG_FILE,
+    "%s; idx:%u, best: DBL_MAX, atime: %g, itime: %g, count: %g\n",
+    info, idx, current_read_time, read_time, record_count);
   }
   else
   {
-    fprintf(DBUG_FILE,"%s; idx: %u, best: %g, current: %g\n",
-            info, idx, join->best_read, read_time);
+    fprintf(DBUG_FILE,
+    "%s; idx:%u, best: %g, atime: %g, itime: %g, count: %g\n",
+    info, idx, join->best_read, current_read_time, read_time, record_count);
   }
 
   /* Print the tables in JOIN->positions */