故障原因：开发人员在主库上修改了一张表的结构，加了一个字段，从库由于各种原因没有同步过去，导致主从同步失败。故障处理：1、查看在从库上查看同步状态：mys
故障原因：
开发人员在主库上修改了一张表的结构，加了一个字段，，从库由于各种原因没有同步过去，导致主从同步失败。
故障处理：
1、查看在从库上查看同步状态：
mysql> show slave status\g*************************** 1. row ***************************slave_io_state: waiting for master to send eventmaster_host: 10.10.100.100master_user: slavemaster_port: 3306connect_retry: 60master_log_file: mysql-bin.000009read_master_log_pos: 917648relay_log_file: mysqld-relay-bin.000017relay_log_pos: 778406relay_master_log_file: mysql-bin.000009slave_io_running: yesslave_sql_running: noreplicate_do_db:replicate_ignore_db: mysql,information_schema,performance_schema,test,mysql,information_schema,performance_schema,testreplicate_do_table:replicate_ignore_table:replicate_wild_do_table:replicate_wild_ignore_table:last_errno: 1054last_error: error 'unknown column 'js_code' in 'field list'' on query. default database: 'web_platform'. query: 'update act_id set js_code='确保该页面的pv埋点已经上报;__tj(node,snode,cid,w,'''','''','''');说明:remark;' where act_id=11'skip_counter: 0exec_master_log_pos: 906099relay_log_space: 790258until_condition: noneuntil_log_file:until_log_pos: 0master_ssl_allowed: nomaster_ssl_ca_file:master_ssl_ca_path:master_ssl_cert:master_ssl_cipher:master_ssl_key:seconds_behind_master: nullmaster_ssl_verify_server_cert: nolast_io_errno: 0last_io_error:last_sql_errno: 1054last_sql_error: error 'unknown column 'js_code' in 'field list'' on query. default database: 'web_platform'. query: 'update act_id set js_code='确保该页面的pv埋点已经上报;__tj(node,snode,cid,w,'''','''','''');说明:remark;' where act_id=11'replicate_ignore_server_ids:master_server_id: 11 row in set (0.00 sec)2、从上面可以看出表act_id的js_code字段在从库上没有，可以对比一下主库和从库这张表的结构：
查看主库：
mysql> desc act_id;+-----------------+------------------+------+-----+---------+----------------+| field| type| null | key | default | extra|+-----------------+------------------+------+-----+---------+----------------+| act_id| int(10) unsigned | no | pri | null | auto_increment || name| varchar(512)| no || null ||| fields| varchar(512)| no || null ||| js_code| text| no || null ||| remark| varchar(512)| no || null ||| create_user| varchar(256)| no || null ||| duty_user_name | varchar(256)| no || null ||| duty_user_email | varchar(256)| yes || null ||| duty_user_phone | varchar(256)| yes || null ||| create_time| bigint(20)| no || null ||| update_time| bigint(20)| no || null ||+-----------------+------------------+------+-----+---------+----------------+11 rows in set (0.00 sec)查看从库：
mysql> desc act_id;+-----------------+------------------+------+-----+---------+----------------+| field| type| null | key | default | extra|+-----------------+------------------+------+-----+---------+----------------+| act_id| int(10) unsigned | no | pri | null | auto_increment || name| varchar(512)| no || null ||| fields| varchar(512)| no || null ||| remark| varchar(512)| no || null ||| create_user| varchar(256)| no || null ||| duty_user_name | varchar(256)| no || null ||| duty_user_email | varchar(256)| yes || null ||| duty_user_phone | varchar(256)| yes || null ||| create_time| bigint(20)| no || null ||| update_time| bigint(20)| no || null ||+-----------------+------------------+------+-----+---------+----------------+10 rows in set (0.00 sec)3、在正式处理故障之前要停掉主库和从库的slave进程（我的环境是做了双向同步，即主主同步）
mysql> slave stop;query ok, 0 rows affected (0.12 sec)4、在从库上加缺少的字段：
alter table act_id add js_code text not null after fields;5、启动从库的slave进程，查看主从状态：
mysql> slave start;query ok, 0 rows affected (0.00 sec)mysql> show slave status\g*************************** 1. row ***************************slave_io_state: waiting for master to send eventmaster_host: 10.10.100.100master_user: slavemaster_port: 3306connect_retry: 60master_log_file: mysql-bin.000009read_master_log_pos: 917648relay_log_file: mysqld-relay-bin.000117relay_log_pos: 253relay_master_log_file: mysql-bin.000009slave_io_running: yesslave_sql_running: yesreplicate_do_db:replicate_ignore_db: mysql,information_schema,performance_schema,test,mysql,information_schema,performance_schema,testreplicate_do_table:replicate_ignore_table:replicate_wild_do_table:replicate_wild_ignore_table:last_errno: 0last_error:skip_counter: 0exec_master_log_pos: 917648relay_log_space: 556until_condition: noneuntil_log_file:until_log_pos: 0master_ssl_allowed: nomaster_ssl_ca_file:master_ssl_ca_path:master_ssl_cert:master_ssl_cipher:master_ssl_key:seconds_behind_master: 0master_ssl_verify_server_cert: nolast_io_errno: 0last_io_error:last_sql_errno: 0last_sql_error:replicate_ignore_server_ids:master_server_id: 11 row in set (0.00 sec)