解决方法，在 my.cnf 中增加 sort_buffer_size=512k 配置项

		
[root@gitlab ~]# cat /etc/my.cnf.d/mysql-server.cnf 
#
# This group are read by MySQL server.
# Use it for options that only the server (but not clients) should see
#
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/en/server-configuration-defaults.html

# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
log-error=/var/log/mysql/mysqld.log
pid-file=/run/mysqld/mysqld.pid


# Add by Neo
character-set-server=utf8mb4
collation-server=utf8mb4_general_ci
explicit_defaults_for_timestamp=true
lower_case_table_names=1
sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION
sort_buffer_size=512k