技术分享 | MySQL史上最快逻辑备份工具
作者：洪斌
爱可生南区负责人兼技术服务总监，MySQL ACE，擅长数据库架构规划、故障诊断、性能优化分析，实践经验丰富，帮助各行业客户解决 MySQL 技术问题，为金融、运营商、互联网等行业客户提供 MySQL 整体解决方案。
本文来源：转载自公众号-玩转MySQL
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MySQL Shell 8.0.21 增加了一种新的逻辑备份恢复方法，有更快的备份恢复效率，支持zstd实时压缩，支持分块并行导出，load data并行导入，还能备份到OCI的对象存储。
- util.dumpInstance() 用于备份整个实例
- util.dumpSchemas() 用于备份指定schema
- util.loadDump() 用于恢复备份
做了个对比测试，在零负载下mysql配置参数不变，备份/恢复相同schema，其中混合了大表和小表，看下这几种方式的实际效果如何。
##对比结果
结论
-
mysql shell
使用默认参数zstd压缩+32M chunk并行导出，恢复时单表可以并行load data，其备份和恢复速度均优于非压缩+非分块。
测试中发现，若禁用压缩，也会禁用分块。 -
mysqldump
备份和恢复都是单线程执行，不压缩的备份效率更快，zstd的实时备份速度比gzip更快，恢复速度最慢。
-
mysqlpump
备份支持并行速度也很快，但是单线程恢复是硬伤。
-
mydumper
默认用gzip协议，备份速度与mysqldump基本一样，看来瓶颈在压缩上。 在非压缩非分块备份速度会更快。 恢复速度中等，单表无法并行。
综合上述测试结果，mysql shell新的备份恢复方式是最快的，得益于使用了zstd实时压缩算法，备份恢复均可以并行，对于单个大表也可以并行。
下面是部分测试过程供参考：
MySQLShell
utli.dumpSchemas/utli.loadDump
- 备份
Acquiring global read lock
All transactions have been started
Locking instance for backup
Global read lock has been released
Writing global DDL files
Preparing data dump for table `test`.`customer1`
Writing DDL for schema `test`
Writing DDL for table `test`.`sbtest1`
Writing DDL for table `test`.`customer1`
Writing DDL for table `test`.`sbtest10`
Data dump for table `test`.`customer1` will be chunked using column `c_w_id`
Preparing data dump for table `test`.`sbtest1`
Data dump for table `test`.`sbtest1` will be chunked using column `id`
Preparing data dump for table `test`.`sbtest10`
Data dump for table `test`.`sbtest10` will be chunked using column `id`
Preparing data dump for table `test`.`sbtest2`
Data dump for table `test`.`sbtest2` will be chunked using column `id`
Preparing data dump for table `test`.`sbtest4`
Data dump for table `test`.`sbtest4` will be chunked using column `id`
Preparing data dump for table `test`.`sbtest6`
Data dump for table `test`.`sbtest6` will be chunked using column `id`
Preparing data dump for table `test`.`sbtest8`
Data dump for table `test`.`sbtest8` will be chunked using column `id`
Running data dump using 4 threads.
NOTE: Progress information uses estimated values and may not be accurate.
Writing DDL for table `test`.`sbtest2`
Writing DDL for table `test`.`sbtest4`
Writing DDL for table `test`.`sbtest6`
Writing DDL for table `test`.`sbtest8`
Data dump for table `test`.`customer1` will be written to 3 files
Data dump for table `test`.`sbtest10` will be written to 1 file
Data dump for table `test`.`sbtest2` will be written to 1 file
Data dump for table `test`.`sbtest4` will be written to 1 file
Data dump for table `test`.`sbtest6` will be written to 1 file
Data dump for table `test`.`sbtest8` will be written to 1 file
Data dump for table `test`.`sbtest1` will be written to 160 files
1 thds dumping - 98% (10.46M rows / ~10.62M rows), 589.52K rows/s, 115.55 MB/s uncompressed, 51.66 MB/s compressed
Duration: 00:00:18s
Schemas dumped: 1
Tables dumped: 7
Uncompressed data size: 2.06 GB
Compressed data size: 922.35 MB
Compression ratio: 2.2
Rows written: 10464999
Bytes written: 922.35 MB
Average uncompressed throughput: 109.46 MB/s
Average compressed throughput: 48.97 MB/s
- 恢复
util.loadDump("test1")
Loading DDL and Data from 'instance' using 4 threads.
Target is MySQL 8.0.21. Dump was produced from MySQL 8.0.21
Checking for pre-existing objects...
Executing common preamble SQL
Executing DDL script for schema `test`
Executing DDL script for `test`.`sbtest1`
Executing DDL script for `test`.`sbtest4`
Executing DDL script for `test`.`sbtest2`
Executing DDL script for `test`.`sbtest8`
Executing DDL script for `test`.`sbtest10`
Executing DDL script for `test`.`sbtest6`
Executing DDL script for `test`.`customer1`
...
[Worker000] test@[email protected]: Records: 65736 Deleted: 0 Skipped: 0 Warnings: 0
Executing common postamble SQL
168 chunks (10.46M rows, 2.06 GB) for 7 tables in 1 schemas were loaded in 1 min 26 sec (avg throughput 23.97 MB/s)
mysqldump
- 备份
/usr/bin/time mysqldump -umsandbox -pmsandbox -h127.0.0.1 -P8021 test | gzip > db.sql.gz
mysqldump: [Warning] Using a password on the command line interface can be insecure.
169.40 real 24.65 user 1.34 sys
- 恢复
/usr/bin/time gzip -d < db.sql.gz | ./use test
257.11 real 9.74 user 0.55 sys
mysqlpump
- 备份
/usr/bin/time mysqlpump --default-parallelism=4 -umsandbox -pmsandbox -h127.0.0.1 -P8021 test | gzip > db2.sql.gz
Dump progress: 6/7 tables, 10421749/10406264 rows
Dump completed in 185352
185.50 real 31.18 user 6.34 sys
- 恢复
/usr/bin/time gzip -d < db2.sql.gz | ./use test
121.17 real 9.66 user 0.76 sys
mydumper/myloader
- 备份
/usr/bin/time mydumper -u msandbox -p msandbox -h 127.0.0.1 -P 8021 -B test -t 4 -v 3 -c -o dumper
** Message: 21:44:55.958: Connected to a MySQL server
** Message: 21:44:56.319: Started dump at: 2020-07-24 21:44:56
** Message: 21:44:56.341: Written master status
** Message: 21:44:56.420: Thread 1 connected using MySQL connection ID 22
** Message: 21:44:56.537: Thread 2 connected using MySQL connection ID 23
** Message: 21:44:56.651: Thread 3 connected using MySQL connection ID 24
** Message: 21:44:56.769: Thread 4 connected using MySQL connection ID 25
** Message: 21:44:56.878: Non-InnoDB dump complete, unlocking tables
** Message: 21:44:56.878: Thread 4 dumping data for `test`.`sbtest10`
** Message: 21:44:56.878: Thread 1 dumping data for `test`.`customer1`
** Message: 21:44:56.878: Thread 3 dumping data for `test`.`sbtest1`
** Message: 21:44:56.878: Thread 2 dumping data for `test`.`sbtest2`
** Message: 21:44:57.139: Thread 2 dumping data for `test`.`sbtest4`
** Message: 21:44:57.143: Thread 4 dumping data for `test`.`sbtest6`
** Message: 21:44:57.396: Thread 2 dumping data for `test`.`sbtest8`
** Message: 21:44:57.398: Thread 4 dumping schema for `test`.`customer1`
** Message: 21:44:57.409: Thread 4 dumping schema for `test`.`sbtest1`
** Message: 21:44:57.419: Thread 4 dumping schema for `test`.`sbtest10`
** Message: 21:44:57.430: Thread 4 dumping schema for `test`.`sbtest2`
** Message: 21:44:57.441: Thread 4 dumping schema for `test`.`sbtest4`
** Message: 21:44:57.453: Thread 4 dumping schema for `test`.`sbtest6`
** Message: 21:44:57.464: Thread 4 dumping schema for `test`.`sbtest8`
** Message: 21:44:57.475: Thread 4 shutting down
** Message: 21:44:57.636: Thread 2 shutting down
** Message: 21:45:03.706: Thread 1 shutting down
** Message: 21:47:40.297: Thread 3 shutting down
** Message: 21:47:40.307: Finished dump at: 2020-07-24 21:47:40
164.54 real 167.58 user 2.28 sys
注：使用的并行备份线程数与dumpSchema相同。
- 恢复
/usr/bin/time myloader -u msandbox -p msandbox -h 127.0.0.1 -P 8021 -B test -t 4 -v 3 -d dumper/
** Message: 23:54:39.961: 4 threads created
** Message: 23:54:39.973: Creating table `test`.`sbtest4`
** Message: 23:54:40.055: Creating table `test`.`sbtest10`
** Message: 23:54:40.127: Creating table `test`.`customer1`
** Message: 23:54:40.201: Creating table `test`.`sbtest8`
** Message: 23:54:40.273: Creating table `test`.`sbtest2`
** Message: 23:54:40.346: Creating table `test`.`sbtest6`
** Message: 23:54:40.423: Creating table `test`.`sbtest1`
** Message: 23:54:40.488: Thread 2 restoring `test`.`sbtest2` part 0
** Message: 23:54:40.488: Thread 3 restoring `test`.`sbtest6` part 0
** Message: 23:54:40.488: Thread 4 restoring `test`.`sbtest8` part 0
** Message: 23:54:40.488: Thread 1 restoring `test`.`sbtest4` part 0
** Message: 23:54:40.833: Thread 2 restoring `test`.`sbtest1` part 0
** Message: 23:54:40.833: Thread 4 restoring `test`.`sbtest10` part 0
** Message: 23:54:40.834: Thread 3 restoring `test`.`customer1` part 0
** Message: 23:54:40.834: Thread 1 shutting down
** Message: 23:54:41.070: Thread 4 shutting down
** Message: 23:54:50.407: Thread 3 shutting down
** Message: 23:57:46.425: Thread 2 shutting down
187.10 real 14.24 user 1.97 sys