對於web應用來說，經常會用到mysql，而數據的備份與還原是web應用經常做的事，一般來說，用客戶端工具phpmyadmin，sqlyog 等，來備份數據庫沒有任何問題，還原時經常碰到mysql提示的#2006錯誤。
2006 (CR_SERVER_GONE_ERROR)Message: MySQL server has gone away
原因可能是sql語句過長，超過mysql通信緩存區最大長度；
調整mysql配置文件中max_allowed_packet
# Example MySQL config file for medium systems. # # This is for a system with little memory (32M - 64M) where MySQL plays # an important part, or systems up to 128M where MySQL is used together with # other programs (such as a web server) # # You can copy this file to # /etc/my.cnf to set global options, # mysql-data-dir/my.cnf to set server-specific options (in this # installation this directory is C:\mysql\data) or # ~/.my.cnf to set user-specific options. # # In this file, you can use all long options that a program supports. # If you want to know which options a program supports, run the program # with the "--help" option. # The following options will be passed to all MySQL clients [client] #password = your_password port = 3306 socket = /tmp/mysql.sock # Here follows entries for some specific programs # The MySQL server [wampmysqld] #mysql端口 port = 3306 socket = /tmp/mysql.sock #索引緩存區，決定你索引查詢時能訪問速度 key_buffer_size = 16M #通信緩存區最大長度，決定你sql語句中字符串最大長度 max_allowed_packet = 1M #排序緩存區，決定你orderby的速度 sort_buffer_size = 512K #通信緩存區大小，查詢時默認該值為通信緩存區大小，若不夠會自動增加直到達到max_allowed_packe net_buffer_length = 8K read_buffer_size = 256K read_rnd_buffer_size = 512K myisam_sort_buffer_size = 8M
