show variables like 'max_connections';
set global max_connections = 200;
(default 151)
show variables like 'innodb_buffer_pool_size';
set global innodb_buffer_pool_size=402653184;
(384MB)
(default 134217728 bytes (128MB))
for permanent, edit /etc/mysql/mysql.conf.d/mysqld.cnf :
max_connections=200
innodb_buffer_pool_size=384M