[mysql] data synchronization prompt: specified key was too long; max key length is 767 bytes

see MYSQL edition ：5.6.45

Database character set ：utf8

Sort rule ：utf8_general_ci

Specified key was too long;max key length is 767 bytes

Google Translate ： The specified key is too long ; The maximum key length is 767 byte

It is found that the length of the index field exceeds the limit ,5.6 The maximum length of the version is 767 byte ;

Generally speaking varchar or text This problem can easily occur when the type is set to index ,utf8 One character takes up 3 byte , If set 255 length , Then for 765 byte ; If the set length is 256, Then for 768 byte ; It's easy to exceed the upper limit .

Solution ：

1. Set the index field length to 255;

2. upgrade mysql edition ;

3. Reduce the index field length to 256 following .