Set group_concat_max_len permanently (MySQL config)

Solution 1:

If you have the setting already in my.cnf or my.cfg, and a restart did not bring about the change you expected, you may just have the setting placed in the wrong location.

Make sure the setting is under the [mysqld] group header

[mysqld]
group_concat_max_len=15360

then you can restart mysqld without worry

BTW @gbn may be more correct in this instance because you cannot use commas in the numerical settings for my.cnf (+1 for @gbn)

Solution 2:

Use group_concat_max_len=15360 without the thousands separator

See the docs

If this doesn't persist, then you need to identify the correct my.cnf or my.cfg used by your installation