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关于数据库:技术分享-MySQL-8021-Disable-Redo-Log-性能测试

jiezi

作者：洪斌
爱可生南区负责人兼技术服务总监，MySQL ACE，善于数据库架构布局、故障诊断、性能优化剖析，实践经验丰盛，帮忙各行业客户解决 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。
本文起源：转载自公众号 - 玩转 MySQL
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记得 5 年前咱们在某银行客户做大数据量 load data 测试时，为了能在要求的工夫内实现数据加载，只管优化了各种参数，但还是防止不了在日志的 IO 开销。

在商业数据库 DB2、Oracle 都有 nologging table 性能，对于有大量数据加载需要的零碎，就能够不记录日志，缩小 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。

最初只好拆分更多实例，减少并行度来进步 load data 效率，来满足时效性要求。

MySQL 始终在改善本身的扩展性，这对于企业级数据库是必须的，不能仅靠拆分打天下，一味的拆分应用体验太差，也会妨碍用户大规模应用，保护分布式架构的复杂性远比集中式简单的多。

昨天公布的 MySQL 8.0.21，咱们看到了 disable redo log 性能，这对 load data 场景太有吸引力了，咱们简略测试下看实际效果如何。

简略比照测试

比照禁用与启用 redo log 两种场景下的执行效率，解决 100w 记录（1.8G）文件，sysbench 标准表构造。

从理论测试状况来看，禁用与启用 redo log 有 10%~30% 的执行工夫差别。

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 性能，能够失常同步。
  • 禁用 redo log 是实例级，不反对表级。
  • 禁用 redo log 若产生 crash 是无奈 recovery 的，OLTP 零碎审慎应用。
  • 实用于大量数据导入场景。
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