mysql binlog初步介绍

mysql
6 minutes read (About 840 words)

binlog 即二进制日志,它记录了数据库上的所有改变，并以二进制的形式保存在磁盘中；
它可以用来查看数据库的变更历史、数据库增量备份和恢复、Mysql的复制（主从数据库的复制）。

mysql binlog解析

binlog有三种格式:

  • Statement 基于SQL语句的复制(statement-based replication,SBR)，
  • Row 基于行的复制(row-based replication,RBR)，
  • Mixed 混合模式复制(mixed-based replication,MBR)。

在我这边mysql 5.7.20版本中默认是使用Row的, 而且默认情况下没有开启binlog

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mysql> select version();
+-----------+
| version() |
+-----------+
| 5.7.20    |
+-----------+
1 row in set (0.00 sec)

mysql>
mysql>
mysql> show variables like 'binlog_format';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| binlog_format | ROW   |
+---------------+-------+
1 row in set (0.00 sec)

mysql> show variables like 'log_bin';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | OFF   |
+---------------+-------+
1 row in set (0.00 sec)

mac环境下开启mysql的binlog

编辑my.cnf文件，对于我来说就是/usr/local/etc/my.cnf文件，在其中增加下面的内容：

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log-bin = /Users/rollenholt/Downloads/mysql/binlog
binlog-format = ROW
server_id = 1

然后brew services restart mysql重启mysql，接下来我们就可以验证mysql的binlog已经开启了：

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mysql> show variables like 'log_bin'
    -> ;
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| log_bin       | ON    |
+---------------+-------+
1 row in set (0.00 sec)

mysql>
mysql> show binary logs;
+---------------+-----------+
| Log_name      | File_size |
+---------------+-----------+
| binlog.000001 |       177 |
| binlog.000002 |       177 |
| binlog.000003 |       177 |
| binlog.000004 |       154 |
+---------------+-----------+
4 rows in set (0.00 sec)

mysql> show master status;
+---------------+----------+--------------+------------------+-------------------+
| File          | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+---------------+----------+--------------+------------------+-------------------+
| binlog.000004 |      154 |              |                  |                   |
+---------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)

mysql> show master logs;
+---------------+-----------+
| Log_name      | File_size |
+---------------+-----------+
| binlog.000001 |       177 |
| binlog.000002 |       177 |
| binlog.000003 |       177 |
| binlog.000004 |       154 |
+---------------+-----------+
4 rows in set (0.00 sec)

同时查看我们配置的log-bin属性对于的目录下：

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~/Downloads/mysql » ls
binlog.000001 binlog.000002 binlog.000003 binlog.000004 binlog.index
------------------------------------------------------------
~/Downloads/mysql » cat binlog.index
/Users/rollenholt/Downloads/mysql/binlog.000001
/Users/rollenholt/Downloads/mysql/binlog.000002
/Users/rollenholt/Downloads/mysql/binlog.000003
/Users/rollenholt/Downloads/mysql/binlog.000004
------------------------------------------------------------
~/Downloads/mysql » cat binlog.000001
_binR �[w{5.7.20-logR �[8


**4SVѶR �[#��_]�hu �[����%                                                                        ------------------------------------------------------------
~/Downloads/mysql »

binlog相关的基本命令：

  • 查看是否开启binlog show variables like 'log_bin'
  • 获取binlog文件列表 show binary logs
  • 查看master上的binlog show master logs

  • 只查看第一个binlog文件的内容

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    mysql> show binlog events;
    +---------------+-----+----------------+-----------+-------------+---------------------------------------+
    | Log_name      | Pos | Event_type     | Server_id | End_log_pos | Info                                  |
    +---------------+-----+----------------+-----------+-------------+---------------------------------------+
    | binlog.000001 |   4 | Format_desc    |         1 |         123 | Server ver: 5.7.20-log, Binlog ver: 4 |
    | binlog.000001 | 123 | Previous_gtids |         1 |         154 |                                       |
    | binlog.000001 | 154 | Stop           |         1 |         177 |                                       |
    +---------------+-----+----------------+-----------+-------------+---------------------------------------+
    3 rows in set (0.01 sec)

  • 查看指定binlog文件的内容 show binlog events in 'binlog.000001'

  • 删除binlog
    • 使用linux命令删除binlog文件
    • 设置binlog的过期时间 使用variable expire_logs_days
    • 手动删除binlog
      • reset master;//删除master的binlog
      • reset slave; //删除slave的中继日志
      • purge master logs before ‘2012-03-30 17:20:00’; //删除指定日期以前的日志索引中binlog日志文件
      • purge master logs to ‘mysql-bin.000002’; //删除指定日志文件的日志索引中binlog日志文件
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mysql> show variables like '%expire_logs_days%';
+------------------+-------+
| Variable_name    | Value |
+------------------+-------+
| expire_logs_days | 0     |
+------------------+-------+
1 row in set (0.00 sec)
  • flush logs 刷新日志
    • 当停止或重启服务器时，服务器会把日志文件记入下一个日志文件，Mysql会在重启时生成一个新的日志文件，文件序号递增；此外，如果日志文件超过max_binlog_size（默认值1G）系统变量配置的上限时，也会生成新的日志文件（在这里需要注意的是，如果你正使用大的事务，二进制日志还会超过max_binlog_size，不会生成新的日志文件，事务全写入一个二进制日志中,这种情况主要是为了保证事务的完整性）；日志被刷新时，新生成一个日志文件。

ERROR 1728 (HY000): Cannot load from mysql.procs_priv. The table is probably corrupted

mysql
2 minutes read (About 352 words)

今天在搞mysql binlog收集时，需要创建一个mysql用户，结果出现了：

ERROR 1728 (HY000): Cannot load from mysql.procs_priv. The table is probably corrupted异常

解决办法:

sudo mysql_upgrade -u root -p

注意后面的用户名和密码自己修改为自己的哈。

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~ » sudo mysql_upgrade -u root -p
Password:
Enter password:
Checking if update is needed.
Checking server version.
Running queries to upgrade MySQL server.
Checking system database.
mysql.columns_priv                                 OK
mysql.db                                           OK
mysql.engine_cost                                  OK
mysql.event                                        OK
mysql.func                                         OK
mysql.general_log                                  OK
mysql.gtid_executed                                OK
mysql.help_category                                OK
mysql.help_keyword                                 OK
mysql.help_relation                                OK
mysql.help_topic                                   OK
mysql.innodb_index_stats                           OK
mysql.innodb_table_stats                           OK
mysql.ndb_binlog_index                             OK
mysql.plugin                                       OK
mysql.proc                                         OK
mysql.procs_priv                                   OK
mysql.proxies_priv                                 OK
mysql.server_cost                                  OK
mysql.servers                                      OK
mysql.slave_master_info                            OK
mysql.slave_relay_log_info                         OK
mysql.slave_worker_info                            OK
mysql.slow_log                                     OK
mysql.tables_priv                                  OK
mysql.time_zone                                    OK
mysql.time_zone_leap_second                        OK
mysql.time_zone_name                               OK
mysql.time_zone_transition                         OK
mysql.time_zone_transition_type                    OK
mysql.user                                         OK
The sys schema is already up to date (version 1.5.1).
Checking databases.
sys.sys_config                                     OK
temp.hsc_biz_system_customer                       OK
temp.hsc_settlement_info                           OK
temp.hsc_settlement_invoice                        OK
temp.hsc_settlement_object                         OK
temp.invoice_config                                OK
test.worker_node                                   OK
test.a                                             OK
test.application                                   OK
test.application_acl                               OK
test.b                                             OK
test.big_table                                     OK
test.certificate_info_tab                          OK
test.company_tab                                   OK
test.connection_config                             OK
test.leader_election                               OK
test.test                                          OK
test.test1                                         OK
test.test_emoij                                    OK
test.user                                          OK
Upgrade process completed successfully.
Checking if update is needed.
------------------------------------------------------------

然后重启mysql以后，在尝试创建用户，发现完美解决。

mysql sleep

mysql
2 minutes read (About 343 words)

今天看到了一个sql：

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select count(*), sleep(5) from test

第一次看到这个sleep函数，所以专门研究了一波。这个函数的语法是：SLEEP(duration), 其中duration的单位是秒

Sleeps (pauses) for the number of seconds given by the duration argument, then returns 0. The duration may have a fractional part. If the argument is NULL or negative, SLEEP() produces a warning, or an error in strict SQL mode.

When sleep returns normally (without interruption), it returns 0:

简单的说他可以让sql在执行的时候sleep一段时间。

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mysql> SELECT SLEEP(1000);
+-------------+
| SLEEP(1000) |
+-------------+
|           0 |
+-------------+

When SLEEP() is the only thing invoked by a query that is interrupted, it returns 1 and the query itself returns no error. This is true whether the query is killed or times out:

  • This statement is interrupted using KILL QUERY from another session:
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mysql> SELECT SLEEP(1000);
+-------------+
| SLEEP(1000) |
+-------------+
|           1 |
+-------------+
  • This statement is interrupted by timing out:
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mysql> SELECT /*+ MAX_EXECUTION_TIME(1) */ SLEEP(1000);
+-------------+
| SLEEP(1000) |
+-------------+
|           1 |
+-------------+

这里解释一下上面的语法，那个语法是Mysql Optimizer Hints

When SLEEP() is only part of a query that is interrupted, the query returns an error:

  • This statement is interrupted using KILL QUERY from another session:
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mysql> SELECT 1 FROM t1 WHERE SLEEP(1000);
ERROR 1317 (70100): Query execution was interrupted
  • This statement is interrupted by timing out:
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mysql> SELECT /*+ MAX_EXECUTION_TIME(1000) */ 1 FROM t1 WHERE SLEEP(1000);
ERROR 3024 (HY000): Query execution was interrupted, maximum statement
execution time exceeded

This function is unsafe for statement-based replication. A warning is logged if you use this function when binlog_format is set to STATEMENT.

参考资料

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