Bug #13117023: Innodb increments handler_read_key when it should not

The counter handler_read_key (SSV::ha_read_key_count) is incremented 
incorrectly.

The mysql server maintains a per thread system_status_var (SSV)
object.  This object contains among other things the counter
SSV::ha_read_key_count. The purpose of this counter is to measure the
number of requests to read a row based on a key (or the number of
index lookups).

This counter was wrongly incremented in the
ha_innobase::innobase_get_index(). The fix removes
this increment statement (for both innodb and innodb_plugin).

The various callers of the innobase_get_index() was checked to
determine if anybody must increment this counter (if they first call
innobase_get_index() and then perform an index lookup).  It was found
that no caller of innobase_get_index() needs to worry about the
SSV::ha_read_key_count counter.

mysql-test/suite/innodb/r/innodb.result

@@ -2365,3 +2365,8 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1
 drop table t1;
 set storage_engine=MyISAM;
+Variable_name	Value
+Handler_read_key	0
+f1
+Variable_name	Value
+Handler_read_key	1

mysql-test/suite/innodb/t/innodb.test

@@ -1389,6 +1389,17 @@ eval set storage_engine=$default;
 -- disable_query_log
 SET GLOBAL innodb_thread_concurrency = @innodb_thread_concurrency_orig;
 
+#
+# Test fix for bug 13117023. InnoDB increments HA_READ_KEY_COUNT (aka
+# HANDLER_READ_KEY) when it should not.
+#
+create table t1 (f1 integer primary key) engine=innodb;
+flush status;
+show status like "handler_read_key";
+select f1 from t1;
+show status like "handler_read_key";
+drop table t1;
+
 #######################################################################
 #                                                                     #
 # Please, DO NOT TOUCH this file as well as the innodb.result file.   #

mysql-test/suite/innodb_plugin/r/innodb.result

@@ -3257,3 +3257,14 @@ Handler_update	1
 Variable_name	Value
 Handler_delete	1
 DROP TABLE bug58912;
+create table t1 (f1 integer primary key) engine=innodb;
+flush status;
+show status like "handler_read_key";
+Variable_name	Value
+Handler_read_key	0
+select f1 from t1;
+f1
+show status like "handler_read_key";
+Variable_name	Value
+Handler_read_key	1
+drop table t1;

mysql-test/suite/innodb_plugin/t/innodb.test

@@ -2571,6 +2571,17 @@ SET GLOBAL innodb_thread_concurrency = @innodb_thread_concurrency_orig;
 # Clean up after the Bug#55284/Bug#58912 test case.
 DROP TABLE bug58912;
 
+#
+# Test fix for bug 13117023. InnoDB increments HA_READ_KEY_COUNT (aka
+# HANDLER_READ_KEY) when it should not.
+#
+create table t1 (f1 integer primary key) engine=innodb;
+flush status;
+show status like "handler_read_key";
+select f1 from t1;
+show status like "handler_read_key";
+drop table t1;
+
 #######################################################################
 #                                                                     #
 # Please, DO NOT TOUCH this file as well as the innodb.result file.   #

storage/innobase/handler/ha_innodb.cc

@@ -4802,7 +4802,6 @@ ha_innobase::innobase_get_index(
 	dict_index_t*	index = 0;
 
 	DBUG_ENTER("innobase_get_index");
-	ha_statistic_increment(&SSV::ha_read_key_count);
 
 	ut_ad(user_thd == ha_thd());
 	ut_a(prebuilt->trx == thd_to_trx(user_thd));

storage/innodb_plugin/ChangeLog

+2011-12-13	The InnoDB Team
+
+	* handler/ha_innodb.cc, innodb.test, innodb.result:
+	Fix Bug#13117023: InnoDB was incrementing the handler_read_key, 
+	also the SSV::ha_read_key_count, at the wrong place.   
+
 2011-12-10	The InnoDB Team
 
 	* include/page0page.h, page/page0page.c:

storage/innodb_plugin/handler/ha_innodb.cc

@@ -5520,7 +5520,6 @@ ha_innobase::innobase_get_index(
 	dict_index_t*	index = 0;
 
 	DBUG_ENTER("innobase_get_index");
-	ha_statistic_increment(&SSV::ha_read_key_count);
 
 	if (keynr != MAX_KEY && table->s->keys > 0) {
 		key = table->key_info + keynr;