MySQL官方对于binlog_format参数的说明：
http://dev.mysql.com/doc/refman/5.5/en/binary-log-setting.html
binlog_format可以动态修改，官网对于动态修改主库配置时提醒谨慎操作，会导致复制关系异常。
【主库flush logs，binlog_format='STATEMENT'】
【从库flush logs，binlog_format='MIXED'】
【主库】
# at 107
#140919 14:17:50 server id 16024 end_log_pos 178 Query thread_id=13 exec_time=0 error_code=0
SET TIMESTAMP=1411107470/*!*/;
BEGIN
/*!*/;
# at 178
#140919 14:17:50 server id 16024 end_log_pos 281 Query thread_id=13 exec_time=0 error_code=0
use jiangxu/*!*/;
SET TIMESTAMP=1411107470/*!*/;
delete from t1 where c1 in (50,51,52)
/*!*/;
# at 281
#140919 14:17:50 server id 16024 end_log_pos 353 Query thread_id=13 exec_time=0 error_code=0
SET TIMESTAMP=1411107470/*!*/;
COMMIT/*!*/;
【从库】
# at 107
#140919 14:17:50 server id 16024 end_log_pos 178 Query thread_id=13 exec_time=253 error_code=0
SET TIMESTAMP=1411107470/*!*/;
BEGIN
/*!*/;
# at 178
#140919 14:17:50 server id 16024 end_log_pos 281 Query thread_id=13 exec_time=253 error_code=0
use `jiangxu`/*!*/;
SET TIMESTAMP=1411107470/*!*/;
delete from t1 where c1 in (50,51,52)
/*!*/;
# at 281
#140919 14:17:50 server id 16024 end_log_pos 353 Query thread_id=13 exec_time=253 error_code=0
SET TIMESTAMP=1411107470/*!*/;
COMMIT/*!*/;
【主库flush logs，binlog_format='MIXED'】
【从库flush logs，binlog_format='MIXED'】
【主库】
# at 107
#140919 14:28:52 server id 16024 end_log_pos 178 Query thread_id=1 exec_time=0 error_code=0
SET TIMESTAMP=1411108132/*!*/;
BEGIN
/*!*/;
# at 178
#140919 14:28:52 server id 16024 end_log_pos 281 Query thread_id=1 exec_time=0 error_code=0
use jiangxu/*!*/;
SET TIMESTAMP=1411108132/*!*/;
delete from t1 where c1 in (40,41,42)
/*!*/;
# at 281
#140919 14:28:52 server id 16024 end_log_pos 308 Xid = 14
COMMIT/*!*/;
【从库】
# at 353
#140919 14:28:52 server id 16024 end_log_pos 412 Query thread_id=1 exec_time=253 error_code=0
SET TIMESTAMP=1411108132/*!*/;
BEGIN
/*!*/;
# at 412
#140919 14:28:52 server id 16024 end_log_pos 515 Query thread_id=1 exec_time=253 error_code=0
SET TIMESTAMP=1411108132/*!*/;
delete from t1 where c1 in (40,41,42)
/*!*/;
# at 515
#140919 14:28:52 server id 16024 end_log_pos 542 Xid = 25540
COMMIT/*!*/;
【主库flush logs，binlog_format='ROW'】
【从库flush logs，binlog_format='MIXED'】
【主库】
# at 107
#140919 14:41:21 server id 16024 end_log_pos 178 Query thread_id=1 exec_time=0 error_code=0
SET TIMESTAMP=1411108881/*!*/;
BEGIN
/*!*/;
# at 178
# at 225
#140919 14:41:21 server id 16024 end_log_pos 225 Table_map: `jiangxu`.`t1` mapped to number 33
#140919 14:41:21 server id 16024 end_log_pos 275 Delete_rows: table id 33 flags: STMT_END_F
### DELETE FROM jiangxu.t1
### WHERE
### @1=30 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
### DELETE FROM jiangxu.t1
### WHERE
### @1=31 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
### DELETE FROM jiangxu.t1
### WHERE
### @1=32 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
# at 275
#140919 14:41:21 server id 16024 end_log_pos 302 Xid = 13
COMMIT/*!*/;
【从库】
# at 542
#140919 14:41:21 server id 16024 end_log_pos 601 Query thread_id=1 exec_time=253 error_code=0
SET TIMESTAMP=1411108881/*!*/;
BEGIN
/*!*/;
# at 601
# at 648
#140919 14:41:21 server id 16024 end_log_pos 648 Table_map: `jiangxu`.`t1` mapped to number 1168
#140919 14:41:21 server id 16024 end_log_pos 698 Delete_rows: table id 1168 flags: STMT_END_F
### DELETE FROM `jiangxu`.`t1`
### WHERE
### @1=30 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
### DELETE FROM `jiangxu`.`t1`
### WHERE
### @1=31 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
### DELETE FROM `jiangxu`.`t1`
### WHERE
### @1=32 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
# at 698
#140919 14:41:21 server id 16024 end_log_pos 725 Xid = 25542
COMMIT/*!*/;
DELIMITER ;
# End of log file
ROLLBACK /* added by mysqlbinlog */;
/*!50003 SET COMPLETION_TYPE=@OLD_COMPLETION_TYPE*/;
【主库flush logs，binlog_format='MIXED'】
【从库flush logs，binlog_format='ROW'】
注意动态修改从库binlog_format因为原session是MIXED，所以需要重建复制关系线程。
【主库】
# at 554
#140919 16:44:50 server id 16024 end_log_pos 625 Query thread_id=3 exec_time=0 error_code=0
SET TIMESTAMP=1411116290/*!*/;
BEGIN
/*!*/;
# at 625
#140919 16:44:50 server id 16024 end_log_pos 728 Query thread_id=3 exec_time=0 error_code=0
SET TIMESTAMP=1411116290/*!*/;
delete from t1 where c1 in (13,14,15)
/*!*/;
# at 728
#140919 16:44:50 server id 16024 end_log_pos 755 Xid = 44
COMMIT/*!*/;
【从库】
# at 296
#140919 16:44:50 server id 16024 end_log_pos 355 Query thread_id=3 exec_time=253 error_code=0
SET TIMESTAMP=1411116290/*!*/;
BEGIN
/*!*/;
# at 355
# at 402
#140919 16:44:50 server id 16024 end_log_pos 402 Table_map: `jiangxu`.`t1` mapped to number 1168
#140919 16:44:50 server id 16024 end_log_pos 452 Delete_rows: table id 1168 flags: STMT_END_F
### DELETE FROM `jiangxu`.`t1`
### WHERE
### @1=13 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
### DELETE FROM `jiangxu`.`t1`
### WHERE
### @1=14 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
### DELETE FROM `jiangxu`.`t1`
### WHERE
### @1=15 /* INT meta=0 nullable=0 is_null=0 */
### @2='a' /* VARSTRING(15) meta=15 nullable=1 is_null=0 */
# at 452
#140919 16:44:50 server id 16024 end_log_pos 479 Xid = 25570
COMMIT/*!*/;
在binlog_format=MIXED时候，哪种改变会被按照ROW进行记录到binlog，参考官方说明：
http://dev.mysql.com/doc/refman/5.5/en/binary-log-mixed.html
所以看得出在MIXED的状态下基本上对于主库的DDL操作无法按照行变化进行记录。
对于行变化的日志记录磁盘IO肯定要比语句复制消耗要大，可以根据架构酌情配置。