feat: tune MariaDB memory usage

roles/mariadb/templates/50-server.cnf.j2

@@ -33,16 +33,16 @@ bind-address            = 127.0.0.1
 #
 
 table_definition_cache  = 800
-join_buffer_size        = 512K
+join_buffer_size        = 1M
 
 key_buffer_size        = 10M
+max_connections        = {{ mariadb_max_connections }}
 #max_allowed_packet     = 1G
 #thread_stack           = 192K
 #thread_cache_size      = 8
 # This replaces the startup script and checks MyISAM tables if needed
 # the first time they are touched
 #myisam_recover_options = BACKUP
-#max_connections        = 100
 #table_cache            = 64
 
 #
@@ -108,7 +108,8 @@ collation-server      = utf8mb4_general_ci
 # Read the manual for more InnoDB related options. There are many!
 # Most important is to give InnoDB 80 % of the system RAM for buffer use:
 # https://mariadb.com/kb/en/innodb-system-variables/#innodb_buffer_pool_size
-#innodb_buffer_pool_size = 8G
+innodb_buffer_pool_size = 256M
+innodb_log_file_size    = 64M
 
 innodb_file_per_table
 innodb_data_file_path=ibdata1:10M:autoextend