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一、前言
从mydumper v0.11.5版本开始,mydumper提供了--load-data参数,使用此参数导出的sql文件将不再是insert语句,而是load data语句。在MySQL官方文档中关于load data是这么描述的:When loading a table from a text file, use LOAD DATA. This is usually 20 times faster than using INSERT statements。load data的导入比insert快20倍,虽然实际中可能很难达到这个效率,但是对于MyDumper/MyLoader来说,使用--load-data选项,对导入速度的提升是显而易见的。
二、--load-data选项
--load-data选项的参数主要有以下几个。使用该选项导出将默认生成dat数据文件,而加上--csv参数将生成csv数据文件。此外也可以自定义数据文件里字段、行的分隔符等,如果不定义,将使用默认的,一般使用默认的就行。- --load-data Instead of creating INSERT INTO statements, it creates LOAD DATA statements and .dat files
- --csv Automatically enables --load-data and set variables to export in CSV format.
- --fields-terminated-by Defines the character that is written between fields
- --fields-enclosed-by Defines the character to enclose fields. Default: "
- --fields-escaped-by Single character that is going to be used to escape characters in theLOAD DATA stament, default: '\'
- --lines-starting-by Adds the string at the begining of each row. When --load-data is usedit is added to the LOAD DATA statement. Its affects INSERT INTO statementsalso when it is used.
- --lines-terminated-by Adds the string at the end of each row. When --load-data is used it isadded to the LOAD DATA statement. Its affects INSERT INTO statementsalso when it is used.
复制代码 三、数据导出
使用--load-data选项进行单库的数据导出:- mydumper -h $host -u $user -p $password -B test -o /mydata/backup/shemafile --load-data --less-locking
复制代码 从以下导出的内容中可以看到,对于每个表除了建表语句的sql文件,还生成了一个包含load语句sql文件,还有一个dat数据文件,里面包含了该表的所有数据。- [root@wusl shemafile]# ll
- total 7651704
- -rw-r--r-- 1 root root 698 Apr 2 11:18 metadata
- -rw-r--r-- 1 root root 1958809525 Apr 2 11:18 test.sbtest1.00000.dat
- -rw-r--r-- 1 root root 319 Apr 2 11:18 test.sbtest1.00000.sql
- -rw-r--r-- 1 root root 402 Apr 2 11:18 test.sbtest1-schema.sql
- -rw-r--r-- 1 root root 1958809801 Apr 2 11:18 test.sbtest2.00000.dat
- -rw-r--r-- 1 root root 319 Apr 2 11:18 test.sbtest2.00000.sql
- -rw-r--r-- 1 root root 402 Apr 2 11:18 test.sbtest2-schema.sql
- -rw-r--r-- 1 root root 1958809332 Apr 2 11:18 test.sbtest3.00000.dat
- -rw-r--r-- 1 root root 319 Apr 2 11:18 test.sbtest3.00000.sql
- -rw-r--r-- 1 root root 402 Apr 2 11:18 test.sbtest3-schema.sql
- -rw-r--r-- 1 root root 1958809678 Apr 2 11:18 test.sbtest4.00000.dat
- -rw-r--r-- 1 root root 319 Apr 2 11:18 test.sbtest4.00000.sql
- -rw-r--r-- 1 root root 402 Apr 2 11:18 test.sbtest4-schema.sql
- -rw-r--r-- 1 root root 153 Apr 2 11:18 test-schema-create.sql
- -rw-r--r-- 1 root root 0 Apr 2 11:18 test-schema-triggers.sql
- [root@wusl shemafile]# more test.sbtest1.00000.dat
- 1 5014614 68487932199-96439406143-93774651418-41631865787-96406072701-20604855487-25459966574-28203206787-41238978918-19503783441 22195207048-70116052123-74140395089-76317954521-98
- 694025897
- 2 5024801 13241531885-45658403807-79170748828-69419634012-13605813761-77983377181-01582588137-21344716829-87370944992-02457486289 28733802923-10548894641-11867531929-71265603657-36
- 546888392
- 3 4989423 51185622598-89397522786-28007882305-52050087550-68686337807-48942386476-96555734557-05264042377-33586177817-31986479495 00592560354-80393027097-78244247549-39135306455-88
- 936868384
- 4 5026450 54133149494-75722987476-23015721680-47254589498-40242947469-55055884969-23675271222-20181439230-74473404563-55407972672 88488171626-98596569412-94026374972-58040528656-38
- 000028170
- [root@wusl shemafile]# more test.sbtest1.00000.sql
- /*!40101 SET NAMES binary*/;
- /*!40014 SET FOREIGN_KEY_CHECKS=0*/;
- /*!40103 SET TIME_ZONE='+00:00' */;
- LOAD DATA LOCAL INFILE 'test.sbtest1.00000.dat' REPLACE INTO TABLE `sbtest1` CHARACTER SET binary FIELDS TERMINATED BY '\t' ENCLOSED BY '' ESCAPED BY '\\' LINES STARTING BY '' TERMINATED
- BY '\n' (`id`,`k`,`c`,`pad`);
复制代码 四、导入速度对比
实验中使用的是sysbench生成的表,数据量9.5G。可以看到使用load-data导入对比insert导入,时间上提升了15%。有一定的提升,但不是特别明显,主要因为是myloader在insert时,也做了很多优化,比如多个insert批量提交,每次提交1000行。- #--load-data导入
- [root@wusl soft]# time myloader -h 10.xx.xx.xx -u root -p xxxxxxxx -d /mydata/backup/shemafile
- ** (myloader:119586): WARNING **: 13:36:34.783: zstd command not found on any static location, use --exec-per-thread for non default locations
- real 2m49.765s
- user 0m4.755s
- sys 0m4.599s
- #insert导入
- [root@wusl soft]# time myloader -h 10.xx.xx.xx -u root -p xxxxxxxx -d /mydata/backup/shemafile
- ** (myloader:122550): WARNING **: 13:45:00.895: zstd command not found on any static location, use --exec-per-thread for non default locations
- real 3m20.258s
- user 0m11.874s
- sys 0m5.455s
复制代码 五、对比MySQL官方mysqlshell的导数工具
MySQL Shell 8.0.21 中推出的Dump & Load工具,同样也是使用load data命令来导入数据,所以理论上和mydumper/myloader使用--load-data效率是一样的。关于mysqlshell的Dump&Load工具,可以参考一下官方陈臣老师的这篇文章:https://mp.weixin.qq.com/s/RC6MykrGbZ850xh3AOjrtw。我们对这两个工具进行一下对比实验,既然是工具对比那就得相对公平,参数环境什么的保持一致,首先导数前重启一下mysql释放buffer pool。mysqlshell导出会默认开压缩和表分片,需要把它关闭。此外,mysqlshell默认是会生成binlog,因此myloader导入时也要加上-e参数开启binlog。- #使用mysqlshell进行数据导出
- MySQL 10.xx.xx.xx:33060+ ssl JS > util.dumpSchemas(['test'],'/mydata/backup/shemafile',{compression: "none",chunking: "false"})
- Acquiring global read lock
- Global read lock acquired
- Initializing - done
- 1 schemas will be dumped and within them 8 tables, 0 views.
- Gathering information - done
- All transactions have been started
- Locking instance for backup
- Global read lock has been released
- Writing global DDL files
- Running data dump using 4 threads.
- NOTE: Progress information uses estimated values and may not be accurate.
- Writing schema metadata - done
- Writing DDL - done
- Writing table metadata - done
- Starting data dump
- 106% (40.00M rows / ~37.59M rows), 323.53K rows/s, 63.45 MB/s
- Dump duration: 00:01:05s
- Total duration: 00:01:05s
- Schemas dumped: 1
- Tables dumped: 8
- Data size: 7.84 GB
- Rows written: 40001025
- Bytes written: 7.84 GB
- Average throughput: 119.52 MB/s
- #使用mysqlshell进行数据导入
- MySQL 10.xx.xx.xx:33060+ ssl JS > util.loadDump("/mydata/backup/shemafile")
- Loading DDL and Data from '/mydata/backup/shemafile' using 4 threads.
- Opening dump...
- Target is MySQL 8.0.31. Dump was produced from MySQL 8.0.31
- Scanning metadata - done
- Checking for pre-existing objects...
- Executing common preamble SQL
- Executing DDL - done
- Executing view DDL - done
- Starting data load
- 2 thds loading | 100% (7.84 GB / 7.84 GB), 24.59 MB/s, 6 / 8 tables done
- Recreating indexes - done
- Executing common postamble SQL
- 8 chunks (40.00M rows, 7.84 GB) for 8 tables in 1 schemas were loaded in 4 min 6 sec (avg throughput 32.03 MB/s)
- 0 warnings were reported during the load.
- #使用myloader导入(写binlog)
- [root@wusl-test-db1-1 soft]# time myloader -h 10.xx.xx.xx -u root -p xxxxxxxx -e -d /mydata/backup/shemafile
- ** (myloader:24020): WARNING **: 15:48:03.796: zstd command not found on any static location, use --exec-per-thread for non default locations
- real 3m44.150s
- user 0m4.855s
- sys 0m4.606s
复制代码 从以上实验可以看出myloader还比mysqlshell导数工具快一点点,我想原因大概是myloader更轻量级,mysqlshell导数工具在数据迁移时可以查看进度、速度等,功能上丰富了不少。
来源:https://www.cnblogs.com/coygfly/p/18112776
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