/usr/local/mysql55/bin/mysqldump -uroot -S /data/mysqldata/3306/mysql.sock --single-transaction --default-character-set=gbk test t10>/usr/tmp/testzsd.sql
--single-transaction
--default-character-set=gbk
test t10
从官方文档看，上面的选项操作分别是：开启了事务，保证数据一致性，设置了默认字符集，选择了test数据库的t10表，但我却想验证上面的操作，是否对我的数据库做了如上操作：
方法：开启general log，观察mysqldump之后的general log日志。
mysql> show variables like '%log%';
mysql> set global general_log=on;
查看相应日志：
120713 15:41:53 20 Connect root@localhost on
20 Query /*!40100 SET @@SQL_MODE='' */
20 Query /*!40103 SET TIME_ZONE='+00:00' */
20 Query
SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ（这里的级别是repeatable read）
20 Query
START TRANSACTION
/*!40100 WITH CONSISTENT SNAPSHOT */（确实开启了日志，为了获得一致性快照）
20 Query UNLOCK TABLES
20 Query SELECT LOGFILE_GROUP_NAME, FILE_NAME, TOTAL_EXTENTS, INITIAL_SIZE, ENGINE, EXTRA FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'UNDO LOG' AND FILE_NAME IS NOT NULL AND LOGFILE_GROUP_NAME IN (SELECT DISTINCT LOGFILE_GROUP_NAME FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'DATAFILE' AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA='test' AND TABLE_NAME IN ('t10'))) GROUP BY LOGFILE_GROUP_NAME, FILE_NAME, ENGINE ORDER BY LOGFILE_GROUP_NAME
120713 15:41:54 20 Query SELECT DISTINCT TABLESPACE_NAME, FILE_NAME, LOGFILE_GROUP_NAME, EXTENT_SIZE, INITIAL_SIZE, ENGINE FROM INFORMATION_SCHEMA.FILES WHERE FILE_TYPE = 'DATAFILE' AND TABLESPACE_NAME IN (SELECT DISTINCT TABLESPACE_NAME FROM INFORMATION_SCHEMA.PARTITIONS WHERE TABLE_SCHEMA='test' AND TABLE_NAME IN ('t10')) ORDER BY TABLESPACE_NAME, LOGFILE_GROUP_NAME
20 Init DB test
20 Query SHOW TABLES LIKE 't10'
20 Query show table status like 't10'
20 Query SET OPTION SQL_QUOTE_SHOW_CREATE=1
20 Query SET SESSION character_set_results = 'binary'
20 Query show create table `t10`
20 Query
SET SESSION character_set_results = 'gbk'
20 Query show fields from `t10`
20 Query
SELECT /*!40001 SQL_NO_CACHE */ * FROM `t10`
120713 15:42:02 20 Query SET SESSION character_set_results = 'binary'
20 Query use `test`
20 Query select @@collation_database
20 Query SHOW TRIGGERS LIKE 't10'
20 Query SET SESSION character_set_results = 'gbk'
20 Quit
从上面的日志可以分析，给与了重复读的事务级别，开启了事务之后，在取读需要dump的数据SELECT /*!40001 SQL_NO_CACHE */ * FROM `t10`。这里是保证数据唯一性的根据和本质。由于重复读的事务级别上面使用了MVCC，保证了数据一致性快照，也不会出现幻读。
