MySQL: Increasing GROUP_CONCAT_MAX_LEN param - any dangers?

问题

Right now, my MySQL server is using the default value of 1024 bytes for the GROUP_CONCAT_MAX_LEN, and I need to increase it.

I am aware of the fact it is constrained by the MAX_ALLOWED_PACKET param, which is currently very sufficient in size.

Will incraesing the GROUP_CONCAT_MAX_LEN affect anything? Does it have any consequences or dangers I should be aware of?

Thanks.

回答1:

Aside from increasing processing time in the MySQL server, and increasing traffic (even locally), no. If you do increase it though, benchmark before and after the change. This way you can be a bit more scientific about your modifications.

I'm not 100% correct, but take a look at this:

http://dev.mysql.com/doc/refman/5.5/en/group-by-functions.html#function_group-concat

来源：https://stackoverflow.com/questions/5019363/mysql-increasing-group-concat-max-len-param-any-dangers