Bug #38773: DROP DATABASE cause switch to stmt-mode when there are temporary tables open

When executing a DROP DATABASE statement in ROW mode and having temporary
tables open at the same time, the existance of temporary tables prevent
the server from switching back to row mode after temporarily switching to
statement mode to handle the logging of the statement.

Fixed the problem by removing the code to switch to statement mode and added
code to temporarily disable the binary log while dropping the objects in the
database.

mysql-test/extra/binlog_tests/database.test:
  Added test to ensure that DROP DATABASE does not affect the replication mode.
mysql-test/suite/binlog/r/binlog_database.result:
  Result file change.
sql/sql_db.cc:
  Removed code that clears the current_stmt_binlog_row_based flag.
  Added code to disable the binary log while dropping the objects
  in a database.

mysql-test/extra/binlog_tests/database.test

@@ -13,3 +13,18 @@ create trigger tr1 before insert on t1 for each row insert into t2 values (2*new
 create procedure sp1 (a int) insert into t1 values(a);
 drop database testing_1;
 source include/show_binlog_events.inc;
+
+# BUG#38773: DROP DATABASE cause switch to stmt-mode when there are
+# temporary tables open
+
+use test;
+reset master;
+create temporary table tt1 (a int);
+create table t1 (a int);
+insert into t1 values (1);
+disable_warnings;
+drop database if exists mysqltest1;
+enable_warnings;
+insert into t1 values (1);
+drop table tt1, t1;
+source include/show_binlog_events.inc;

mysql-test/suite/binlog/r/binlog_database.result

@@ -17,6 +17,22 @@ master-bin.000001	#	Query	#	#	use `testing_1`; CREATE DEFINER=`root`@`localhost`
 master-bin.000001	#	Query	#	#	use `testing_1`; CREATE DEFINER=`root`@`localhost` PROCEDURE `sp1`(a int)
 insert into t1 values(a)
 master-bin.000001	#	Query	#	#	drop database testing_1
+use test;
+reset master;
+create temporary table tt1 (a int);
+create table t1 (a int);
+insert into t1 values (1);
+drop database if exists mysqltest1;
+insert into t1 values (1);
+drop table tt1, t1;
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	#	#	use `test`; create temporary table tt1 (a int)
+master-bin.000001	#	Query	#	#	use `test`; create table t1 (a int)
+master-bin.000001	#	Query	#	#	use `test`; insert into t1 values (1)
+master-bin.000001	#	Query	#	#	drop database if exists mysqltest1
+master-bin.000001	#	Query	#	#	use `test`; insert into t1 values (1)
+master-bin.000001	#	Query	#	#	use `test`; drop table tt1, t1
 set binlog_format=mixed;
 reset master;
 create database testing_1;
@@ -36,6 +52,22 @@ master-bin.000001	#	Query	#	#	use `testing_1`; CREATE DEFINER=`root`@`localhost`
 master-bin.000001	#	Query	#	#	use `testing_1`; CREATE DEFINER=`root`@`localhost` PROCEDURE `sp1`(a int)
 insert into t1 values(a)
 master-bin.000001	#	Query	#	#	drop database testing_1
+use test;
+reset master;
+create temporary table tt1 (a int);
+create table t1 (a int);
+insert into t1 values (1);
+drop database if exists mysqltest1;
+insert into t1 values (1);
+drop table tt1, t1;
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	#	#	use `test`; create temporary table tt1 (a int)
+master-bin.000001	#	Query	#	#	use `test`; create table t1 (a int)
+master-bin.000001	#	Query	#	#	use `test`; insert into t1 values (1)
+master-bin.000001	#	Query	#	#	drop database if exists mysqltest1
+master-bin.000001	#	Query	#	#	use `test`; insert into t1 values (1)
+master-bin.000001	#	Query	#	#	use `test`; drop table tt1, t1
 set binlog_format=row;
 reset master;
 create database testing_1;
@@ -55,6 +87,27 @@ master-bin.000001	#	Query	#	#	use `testing_1`; CREATE DEFINER=`root`@`localhost`
 master-bin.000001	#	Query	#	#	use `testing_1`; CREATE DEFINER=`root`@`localhost` PROCEDURE `sp1`(a int)
 insert into t1 values(a)
 master-bin.000001	#	Query	#	#	drop database testing_1
+use test;
+reset master;
+create temporary table tt1 (a int);
+create table t1 (a int);
+insert into t1 values (1);
+drop database if exists mysqltest1;
+insert into t1 values (1);
+drop table tt1, t1;
+show binlog events from <binlog_start>;
+Log_name	Pos	Event_type	Server_id	End_log_pos	Info
+master-bin.000001	#	Query	#	#	use `test`; create table t1 (a int)
+master-bin.000001	#	Query	#	#	use `test`; BEGIN
+master-bin.000001	#	Table_map	#	#	table_id: # (test.t1)
+master-bin.000001	#	Write_rows	#	#	table_id: # flags: STMT_END_F
+master-bin.000001	#	Query	#	#	use `test`; COMMIT
+master-bin.000001	#	Query	#	#	drop database if exists mysqltest1
+master-bin.000001	#	Query	#	#	use `test`; BEGIN
+master-bin.000001	#	Table_map	#	#	table_id: # (test.t1)
+master-bin.000001	#	Write_rows	#	#	table_id: # flags: STMT_END_F
+master-bin.000001	#	Query	#	#	use `test`; COMMIT
+master-bin.000001	#	Query	#	#	use `test`; DROP TABLE `t1` /* generated by server */
 show databases;
 Database
 information_schema

sql/sql_db.cc

@@ -883,13 +883,6 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
 
   VOID(pthread_mutex_lock(&LOCK_mysql_create_db));
 
-  /*
-    This statement will be replicated as a statement, even when using
-    row-based replication. The flag will be reset at the end of the
-    statement.
-  */
-  thd->clear_current_stmt_binlog_row_based();
-
   length= build_table_filename(path, sizeof(path), db, "", "", 0);
   strmov(path+length, MY_DB_OPT_FILE);		// Append db option file name
   del_dbopt(path);				// Remove dboption hash entry
@@ -914,8 +907,21 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
     remove_db_from_cache(db);
     pthread_mutex_unlock(&LOCK_open);
 
-    
     error= -1;
+    /*
+      We temporarily disable the binary log while dropping the objects
+      in the database. Since the DROP DATABASE statement is always
+      replicated as a statement, execution of it will drop all objects
+      in the database on the slave as well, so there is no need to
+      replicate the removal of the individual objects in the database
+      as well.
+
+      This is more of a safety precaution, since normally no objects
+      should be dropped while the database is being cleaned, but in
+      the event that a change in the code to remove other objects is
+      made, these drops should still not be logged.
+     */
+    tmp_disable_binlog(thd);
     if ((deleted= mysql_rm_known_files(thd, dirp, db, path, 0,
                                        &dropped_tables)) >= 0)
     {
@@ -927,6 +933,7 @@ bool mysql_rm_db(THD *thd,char *db,bool if_exists, bool silent)
 #endif
       error = 0;
     }
+    reenable_binlog(thd);
   }
   if (!silent && deleted>=0)
   {