mysql主從復(fù)制是最常見的高可用方式，通過(guò)主-從的方式，實(shí)現(xiàn)系統(tǒng)的高可用。在生產(chǎn)環(huán)境種，通常采用一主多從的方式，通過(guò)主庫(kù)寫數(shù)據(jù)，從庫(kù)讀數(shù)據(jù)，來(lái)提升系統(tǒng)的性能。
現(xiàn)在就演示一下，mysql5.7之下，如何配置主從復(fù)制。
1. 環(huán)境準(zhǔn)備
兩臺(tái)安裝好mysql數(shù)據(jù)庫(kù)的服務(wù)器如下：
| 序號(hào) | 服務(wù)器IP | 主/從 | mysql版本 |
|---|---|---|---|
| 1 | 192.168.161.114 | 主 | 5.7.34 |
| 2 | 192.168.161.115 | 從 | 5.7.34 |
2.主庫(kù)配置
查看主庫(kù)log配置：
mysql> show global variables like '%log%';
+--------------------------------------------+------------------------------------------+
| Variable_name | Value |
+--------------------------------------------+------------------------------------------+
| back_log | 300 |
| binlog_cache_size | 1048576 |
| binlog_checksum | CRC32 |
| binlog_direct_non_transactional_updates | OFF |
| binlog_error_action | ABORT_SERVER |
| binlog_format | MIXED |
| binlog_group_commit_sync_delay | 0 |
| binlog_group_commit_sync_no_delay_count | 0 |
| binlog_gtid_simple_recovery | ON |
| binlog_max_flush_queue_time | 0 |
| binlog_order_commits | ON |
| binlog_row_image | FULL |
| binlog_rows_query_log_events | OFF |
| binlog_stmt_cache_size | 32768 |
| binlog_transaction_dependency_history_size | 25000 |
| binlog_transaction_dependency_tracking | COMMIT_ORDER |
| expire_logs_days | 30 |
| general_log | OFF |
| general_log_file | /opt/mysql/data/m161p114.log |
| innodb_api_enable_binlog | OFF |
| innodb_flush_log_at_timeout | 1 |
| innodb_flush_log_at_trx_commit | 2 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_buffer_size | 2097152 |
| innodb_log_checksums | ON |
| innodb_log_compressed_pages | ON |
| innodb_log_file_size | 33554432 |
| innodb_log_files_in_group | 3 |
| innodb_log_group_home_dir | ./ |
| innodb_log_write_ahead_size | 8192 |
| innodb_max_undo_log_size | 1073741824 |
| innodb_online_alter_log_max_size | 134217728 |
| innodb_undo_log_truncate | OFF |
| innodb_undo_logs | 128 |
| log_bin | ON |
| log_bin_basename | /opt/mysql/data/mysql-bin |
| log_bin_index | /opt/mysql/data/mysql-bin.index |
| log_bin_trust_function_creators | OFF |
| log_bin_use_v1_row_events | OFF |
| log_builtin_as_identified_by_password | OFF |
| log_error | /opt/mysql/log/mysql-error.log |
| log_error_verbosity | 3 |
| log_output | FILE |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_admin_statements | OFF |
| log_slow_slave_statements | OFF |
| log_statements_unsafe_for_binlog | ON |
| log_syslog | OFF |
| log_syslog_facility | daemon |
| log_syslog_include_pid | ON |
| log_syslog_tag | |
| log_throttle_queries_not_using_indexes | 0 |
| log_timestamps | UTC |
| log_warnings | 2 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 1073741824 |
| max_binlog_stmt_cache_size | 18446744073709547520 |
| max_relay_log_size | 0 |
| relay_log | |
| relay_log_basename | /opt/mysql/data/m161p114-relay-bin |
| relay_log_index | /opt/mysql/data/m161p114-relay-bin.index |
| relay_log_info_file | relay-log.info |
| relay_log_info_repository | FILE |
| relay_log_purge | ON |
| relay_log_recovery | OFF |
| relay_log_space_limit | 0 |
| slow_query_log | ON |
| slow_query_log_file | /opt/mysql/log/mysql-slow.log |
| sql_log_off | OFF |
| sync_binlog | 1 |
| sync_relay_log | 10000 |
| sync_relay_log_info | 10000 |
+--------------------------------------------+------------------------------------------+
73 rows in set (0.01 sec)
查看主庫(kù)日志文件：
mysql> show master logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 177 |
| mysql-bin.000002 | 711 |
| mysql-bin.000003 | 1225 |
| mysql-bin.000004 | 177 |
| mysql-bin.000005 | 154 |
+------------------+-----------+
5 rows in set (0.00 sec)
查看主庫(kù)server相關(guān)配置：
mysql> show global variables like '%server%';
+---------------------------------+--------------------------------------+
| Variable_name | Value |
+---------------------------------+--------------------------------------+
| character_set_server | utf8 |
| collation_server | utf8_general_ci |
| innodb_ft_server_stopword_table | |
| server_id | 1 |
| server_id_bits | 32 |
| server_uuid | 10dfcf35-16c2-11ec-9238-5254003c7ee2 |
+---------------------------------+--------------------------------------+
6 rows in set (0.00 sec)
主庫(kù)創(chuàng)建一個(gè)用于復(fù)制的用戶：
mysql> create user 'repl'@'%' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
將replication slave,replication client 授權(quán)到repl用戶：
mysql> grant replication slave,replication client on *.* to 'repl'@'%';
Query OK, 0 rows affected (0.00 sec)
刷新權(quán)限：
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
查看主庫(kù)status:
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000005 | 767 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
可以看到，此時(shí)主庫(kù)當(dāng)前日志的最后一個(gè)文件為005，且position為767.
2.從庫(kù)配置
查看從庫(kù)的log配置：
mysql> show global variables like '%log%';
+--------------------------------------------+---------------------------------------+
| Variable_name | Value |
+--------------------------------------------+---------------------------------------+
| back_log | 300 |
| binlog_cache_size | 1048576 |
| binlog_checksum | CRC32 |
| binlog_direct_non_transactional_updates | OFF |
| binlog_error_action | ABORT_SERVER |
| binlog_format | MIXED |
| binlog_group_commit_sync_delay | 0 |
| binlog_group_commit_sync_no_delay_count | 0 |
| binlog_gtid_simple_recovery | ON |
| binlog_max_flush_queue_time | 0 |
| binlog_order_commits | ON |
| binlog_row_image | FULL |
| binlog_rows_query_log_events | OFF |
| binlog_stmt_cache_size | 32768 |
| binlog_transaction_dependency_history_size | 25000 |
| binlog_transaction_dependency_tracking | COMMIT_ORDER |
| expire_logs_days | 30 |
| general_log | OFF |
| general_log_file | /opt/mysql/data/m161p115.log |
| innodb_api_enable_binlog | OFF |
| innodb_flush_log_at_timeout | 1 |
| innodb_flush_log_at_trx_commit | 2 |
| innodb_locks_unsafe_for_binlog | OFF |
| innodb_log_buffer_size | 2097152 |
| innodb_log_checksums | ON |
| innodb_log_compressed_pages | ON |
| innodb_log_file_size | 33554432 |
| innodb_log_files_in_group | 3 |
| innodb_log_group_home_dir | ./ |
| innodb_log_write_ahead_size | 8192 |
| innodb_max_undo_log_size | 1073741824 |
| innodb_online_alter_log_max_size | 134217728 |
| innodb_undo_log_truncate | OFF |
| innodb_undo_logs | 128 |
| log_bin | ON |
| log_bin_basename | /opt/mysql/data/mysql-bin |
| log_bin_index | /opt/mysql/data/mysql-bin.index |
| log_bin_trust_function_creators | OFF |
| log_bin_use_v1_row_events | OFF |
| log_builtin_as_identified_by_password | OFF |
| log_error | /opt/mysql/log/mysql-error.log |
| log_error_verbosity | 3 |
| log_output | FILE |
| log_queries_not_using_indexes | OFF |
| log_slave_updates | OFF |
| log_slow_admin_statements | OFF |
| log_slow_slave_statements | OFF |
| log_statements_unsafe_for_binlog | ON |
| log_syslog | OFF |
| log_syslog_facility | daemon |
| log_syslog_include_pid | ON |
| log_syslog_tag | |
| log_throttle_queries_not_using_indexes | 0 |
| log_timestamps | UTC |
| log_warnings | 2 |
| max_binlog_cache_size | 18446744073709547520 |
| max_binlog_size | 1073741824 |
| max_binlog_stmt_cache_size | 18446744073709547520 |
| max_relay_log_size | 0 |
| relay_log | slave-relay-bin |
| relay_log_basename | /opt/mysql/data/slave-relay-bin |
| relay_log_index | /opt/mysql/data/slave-relay-bin.index |
| relay_log_info_file | relay-log.info |
| relay_log_info_repository | FILE |
| relay_log_purge | ON |
| relay_log_recovery | OFF |
| relay_log_space_limit | 0 |
| slow_query_log | ON |
| slow_query_log_file | /opt/mysql/log/mysql-slow.log |
| sql_log_off | OFF |
| sync_binlog | 1 |
| sync_relay_log | 10000 |
| sync_relay_log_info | 10000 |
+--------------------------------------------+---------------------------------------+
73 rows in set (0.01 sec)
查看從庫(kù)的server配置：
mysql> show global variables like '%server%';
+---------------------------------+--------------------------------------+
| Variable_name | Value |
+---------------------------------+--------------------------------------+
| character_set_server | utf8 |
| collation_server | utf8_general_ci |
| innodb_ft_server_stopword_table | |
| server_id | 2 |
| server_id_bits | 32 |
| server_uuid | 03cb46fa-16bc-11ec-9550-525400ea020a |
+---------------------------------+--------------------------------------+
6 rows in set (0.00 sec)
查看從庫(kù)的master日志：
mysql> show master logs;
+------------------+-----------+
| Log_name | File_size |
+------------------+-----------+
| mysql-bin.000001 | 177 |
| mysql-bin.000002 | 711 |
| mysql-bin.000003 | 1225 |
| mysql-bin.000004 | 177 |
| mysql-bin.000005 | 177 |
| mysql-bin.000006 | 154 |
+------------------+-----------+
6 rows in set (0.00 sec)
查看從庫(kù)的status:
mysql> show master status;
+------------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------------+----------+--------------+------------------+-------------------+
| mysql-bin.000006 | 154 | | | |
+------------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
現(xiàn)在對(duì)從庫(kù)進(jìn)行配置：
mysql> change master to master_host='192.168.161.114',master_user='repl',master_password='123456',master_log_file='mysql-bin.000005',master_log_pos=767;
Query OK, 0 rows affected, 2 warnings (0.02 sec)
需要注意的是，master_log_file 與master_log_pos 均要指向主庫(kù)對(duì)應(yīng)的日志文件的最后一個(gè)文件。
此處的指向?yàn)榍懊娴谝徊糠种胁榭吹娜罩镜闹祄aster_log_file='mysql-bin.000005',master_log_pos=767。
3.啟動(dòng)從庫(kù)
查看從庫(kù)的status:
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State:
Master_Host: 192.168.161.114
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000005
Read_Master_Log_Pos: 767
Relay_Log_File: slave-relay-bin.000001
Relay_Log_Pos: 4
Relay_Master_Log_File: mysql-bin.000005
Slave_IO_Running: No
Slave_SQL_Running: No
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 767
Relay_Log_Space: 154
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 0
Master_UUID:
Master_Info_File: /opt/mysql/data/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.01 sec)
ERROR:
No query specified
因?yàn)闆](méi)有啟動(dòng)從節(jié)點(diǎn)的復(fù)制線程，這兩個(gè)參數(shù)都為NO.
Slave_IO_Running: No
Slave_SQL_Running: No
現(xiàn)在啟動(dòng)主從復(fù)制：
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
再次查看從庫(kù)節(jié)點(diǎn)的狀態(tài)：
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.161.114
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000005
Read_Master_Log_Pos: 767
Relay_Log_File: slave-relay-bin.000002
Relay_Log_Pos: 320
Relay_Master_Log_File: mysql-bin.000005
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 767
Relay_Log_Space: 527
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1
Master_UUID: 10dfcf35-16c2-11ec-9238-5254003c7ee2
Master_Info_File: /opt/mysql/data/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for more updates
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp:
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
ERROR:
No query specified
可以看到這兩個(gè)參數(shù)都為yes.
Slave_IO_Running: Yes
Slave_SQL_Running: Yes。
需要注意的是，并不是所有的庫(kù)操作都要同步到從庫(kù)，因此，可以在主庫(kù)的配置上增加如下配置:
# 不同步哪些數(shù)據(jù)庫(kù)
binlog-ignore-db = mysql
binlog-ignore-db = test
binlog-ignore-db = information_schema
# 只同步哪些數(shù)據(jù)庫(kù)，除此之外，其他不同步
binlog-do-db = gts
這樣可以將需要同步的數(shù)據(jù)庫(kù)進(jìn)行指定。
4.主從不一致問(wèn)題
不小心在從庫(kù)上執(zhí)行了寫操作，這樣導(dǎo)致從庫(kù)的Slave_SQL_Running停止：
mysql> show slave status\G;
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.161.114
Master_User: repl
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000006
Read_Master_Log_Pos: 509
Relay_Log_File: slave-relay-bin.000005
Relay_Log_Pos: 367
Relay_Master_Log_File: mysql-bin.000006
Slave_IO_Running: Yes
Slave_SQL_Running: No
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 1008
Last_Error: Error 'Can't drop database 'gts'; database doesn't exist' on query. Default database: 'gts'. Query: 'drop database gts'
Skip_Counter: 0
Exec_Master_Log_Pos: 154
Relay_Log_Space: 1095
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: NULL
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 1008
Last_SQL_Error: Error 'Can't drop database 'gts'; database doesn't exist' on query. Default database: 'gts'. Query: 'drop database gts'
Replicate_Ignore_Server_Ids:
Master_Server_Id: 1
Master_UUID: 10dfcf35-16c2-11ec-9238-5254003c7ee2
Master_Info_File: /opt/mysql/data/master.info
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State:
Master_Retry_Count: 86400
Master_Bind:
Last_IO_Error_Timestamp:
Last_SQL_Error_Timestamp: 210917 20:18:56
Master_SSL_Crl:
Master_SSL_Crlpath:
Retrieved_Gtid_Set:
Executed_Gtid_Set:
Auto_Position: 0
Replicate_Rewrite_DB:
Channel_Name:
Master_TLS_Version:
1 row in set (0.00 sec)
解決辦法,如果主從不同步，可以通過(guò)如下方法強(qiáng)行跳過(guò)：
mysql> stop slave;
Query OK, 0 rows affected (0.00 sec)
mysql> set global sql_slave_skip_counter=1;
Query OK, 0 rows affected (0.00 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
強(qiáng)行跳過(guò)之后，主從就能一致了。
現(xiàn)在在主庫(kù)上創(chuàng)建一個(gè)gts數(shù)據(jù)庫(kù)，從庫(kù)上就能同步到了。
主庫(kù)執(zhí)行如下語(yǔ)句：
create database gts DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;
從庫(kù)下就能查詢到了：
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| gts |
| mysql |
| performance_schema |
| sys |
+--------------------+
5 rows in set (0.01 sec)
這說(shuō)明，從庫(kù)上要設(shè)置為只讀：
設(shè)置：read_only = ON,但是此限制對(duì)擁有SUPER權(quán)限 的用戶均無(wú)效。
阻止所有用戶的方法,在從庫(kù)上執(zhí)行如下語(yǔ)句：
mysql> flush tables with read lock;
Query OK, 0 rows affected (0.00 sec)
至此，mysql的主從復(fù)制配置完成。
