Fix for bug #28808: log_queries_not_using_indexes variable dynamic change is ignored

Problem: logging queries not using indexes we check a special flag which 
is set only at the server startup and is not changing with a corresponding
server variable together.

Fix: check the variable value instead of the flag.

mysql-test/r/show_check.result

@@ -1088,4 +1088,34 @@ DROP TABLE t1;
 DROP VIEW v1;
 DROP PROCEDURE p1;
 DROP FUNCTION f1;
+flush status;
+show variables like "log_queries_not_using_indexes";
+Variable_name	Value
+log_queries_not_using_indexes	ON
+select 1 from information_schema.tables limit 1;
+1
+1
+show status like 'slow_queries';
+Variable_name	Value
+Slow_queries	1
+set global log_queries_not_using_indexes=OFF;
+show variables like "log_queries_not_using_indexes";
+Variable_name	Value
+log_queries_not_using_indexes	OFF
+select 1 from information_schema.tables limit 1;
+1
+1
+show status like 'slow_queries';
+Variable_name	Value
+Slow_queries	1
+set global log_queries_not_using_indexes=ON;
+show variables like "log_queries_not_using_indexes";
+Variable_name	Value
+log_queries_not_using_indexes	ON
+select 1 from information_schema.tables limit 1;
+1
+1
+show status like 'slow_queries';
+Variable_name	Value
+Slow_queries	2
 End of 5.0 tests

mysql-test/t/show_check.test

@@ -766,4 +766,20 @@ DROP VIEW v1;
 DROP PROCEDURE p1;
 DROP FUNCTION f1;
 
+#
+# Bug #28808: log_queries_not_using_indexes variable dynamic change is ignored
+#
+flush status;
+show variables like "log_queries_not_using_indexes";
+select 1 from information_schema.tables limit 1;
+show status like 'slow_queries';
+set global log_queries_not_using_indexes=OFF;
+show variables like "log_queries_not_using_indexes";
+select 1 from information_schema.tables limit 1;
+show status like 'slow_queries';
+set global log_queries_not_using_indexes=ON;
+show variables like "log_queries_not_using_indexes";
+select 1 from information_schema.tables limit 1;
+show status like 'slow_queries';
+
 --echo End of 5.0 tests

sql/mysqld.cc

@@ -7461,8 +7461,6 @@ static void get_options(int argc,char **argv)
 
   if (opt_short_log_format)
     opt_specialflag|= SPECIAL_SHORT_LOG_FORMAT;
-  if (opt_log_queries_not_using_indexes)
-    opt_specialflag|= SPECIAL_LOG_QUERIES_NOT_USING_INDEXES;
 
   if (init_global_datetime_format(MYSQL_TIMESTAMP_DATE,
 				  &global_system_variables.date_format) ||

sql/sql_parse.cc

@@ -2207,7 +2207,7 @@ void log_slow_statement(THD *thd)
 	thd->variables.long_query_time ||
         (thd->server_status &
 	  (SERVER_QUERY_NO_INDEX_USED | SERVER_QUERY_NO_GOOD_INDEX_USED)) &&
-        (specialflag & SPECIAL_LOG_QUERIES_NOT_USING_INDEXES) &&
+        opt_log_queries_not_using_indexes &&
         /* == SQLCOM_END unless this is a SHOW command */
         thd->lex->orig_sql_command == SQLCOM_END)
     {

sql/unireg.h

@@ -120,7 +120,7 @@
 #define SPECIAL_NO_HOST_CACHE	512		/* Don't cache hosts */
 #define SPECIAL_SHORT_LOG_FORMAT 1024
 #define SPECIAL_SAFE_MODE	2048
-#define SPECIAL_LOG_QUERIES_NOT_USING_INDEXES 4096 /* Log q not using indexes */
+#define SPECIAL_LOG_QUERIES_NOT_USING_INDEXES 4096 /* Obsolete */
 
 	/* Extern defines */
 #define store_record(A,B) bmove_align((A)->B,(A)->record[0],(size_t) (A)->s->reclength)