技术分享 | MySQL 8.0.21 Disable Redo Log 性能测试

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。
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记得 5 年前我们在某银行客户做大数据量 load data 测试时,为了能在要求的时间内完成数据加载,尽管优化了各种参数,但还是避免不了在日志的 IO 开销。

在商业数据库 DB2、Oracle 都有 nologging table 功能,对于有大量数据加载需求的系统,就可以不记录日志,减少 IO 的开销。
这对用惯了商业数据库的用户来说,首测尝试开源数据库,感觉各种不适应。

最后只好拆分更多实例,增加并行度来提高 load data 效率,来满足时效性要求。

MySQL 一直在改善自身的扩展性,这对于企业级数据库是必须的,不能仅靠拆分打天下,一味的拆分使用体验太差,也会阻碍用户大规模使用,维护分布式架构的复杂性远比集中式复杂的多。

昨天发布的 MySQL 8.0.21 ,我们看到了 disable redo log 功能,这对 load data 场景太有吸引力了,我们简单测试下看实际效果如何。

简单对比测试

对比禁用与启用 redo log 两种场景下的执行效率,处理 100w 记录(1.8G)文件,sysbench 标准表结构。
技术分享 | MySQL 8.0.21 Disable Redo Log 性能测试_第1张图片

从实际测试情况来看,禁用与启用 redo log 有 10%~30% 的执行时间差异。

禁用 redo log load data

mysql [localhost:8021] {msandbox} (test) > ALTER INSTANCE DISABLE INNODB REDO_LOG;
Query OK, 0 rows affected (0.10 sec)

mysql [localhost:8021] {msandbox} (test) > load data infile 'sbtest.txt' into table sbtest1;
Query OK, 10000000 rows affected (2 min 39.66 sec)
Records: 10000000  Deleted: 0  Skipped: 0  Warnings: 0

mysql [localhost:8021] {msandbox} (test) > truncate sbtest1;
Query OK, 0 rows affected (0.36 sec)

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=0;set global innodb_flush_log_at_trx_commit=0;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)
mysql [localhost:8021] {msandbox} (test) > load data infile 'sbtest.txt' into table sbtest1;
Query OK, 10000000 rows affected (2 min 30.61 sec)
Records: 10000000  Deleted: 0  Skipped: 0  Warnings: 0

启用 redo log load data

mysql [localhost:8021] {msandbox} (test) > ALTER INSTANCE ENABLE INNODB REDO_LOG;
Query OK, 0 rows affected (0.09 sec)

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=1;set global innodb_flush_log_at_trx_commit=1;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > load data infile 'sbtest.txt' into table sbtest1;
Query OK, 10000000 rows affected (3 min 37.55 sec)
Records: 10000000  Deleted: 0  Skipped: 0  Warnings: 0

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=0;set global innodb_flush_log_at_trx_commit=0;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > truncate sbtest1;
Query OK, 0 rows affected (0.34 sec)

mysql [localhost:8021] {msandbox} (test) > load data infile 'sbtest.txt' into table sbtest1;
Query OK, 10000000 rows affected (2 min 49.84 sec)
Records: 10000000  Deleted: 0  Skipped: 0  Warnings: 0

禁用 redo log add index

mysql [localhost:8021] {msandbox} (test) > ALTER INSTANCE DISABLE INNODB REDO_LOG;
Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=1;set global innodb_flush_log_at_trx_commit=1;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > alter table sbtest1 add index idx_c(c);
Query OK, 0 rows affected (38.96 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=0;set global innodb_flush_log_at_trx_commit=0;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > alter table sbtest1 drop index idx_c;
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql [localhost:8021] {msandbox} (test) > alter table sbtest1 add index idx_c(c);
Query OK, 0 rows affected (35.13 sec)
Records: 0  Duplicates: 0  Warnings: 0

启用 redo log add index

mysql [localhost:8021] {msandbox} (test) > ALTER INSTANCE ENABLE INNODB REDO_LOG;
Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=1;set global innodb_flush_log_at_trx_commit=1;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > alter table sbtest1 add index idx_c(c);
Query OK, 0 rows affected (47.05 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql [localhost:8021] {msandbox} (test) > set global sync_binlog=0;set global innodb_flush_log_at_trx_commit=0;
Query OK, 0 rows affected (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

mysql [localhost:8021] {msandbox} (test) > alter table sbtest1 drop index idx_c;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql [localhost:8021] {msandbox} (test) > alter table sbtest1 add index idx_c(c);
Query OK, 0 rows affected (47.32 sec)
Records: 0  Duplicates: 0  Warnings: 0

总结一下

  • 禁用 redo log 不影响 binlog 功能,可以正常同步。
  • 禁用 redo log 是实例级,不支持表级。
  • 禁用 redo log若发生 crash 是无法 recovery 的,OLTP 系统谨慎使用。
  • 适用于大量数据导入场景。

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