add performance_schema property

docs/configuration.md

@@ -74,3 +74,22 @@ See the [proxy](jobs/proxy/spec) and [acceptance-tests](jobs/acceptance-tests/sp
 The slow query log is enabled and you can find long query exceeded 10 seconds (by default) in `/var/vcap/sys/log/mysql/mysql_slow_query.log`
 
 To change the threshold above which SQL queries get logged in the slow query log file, update  `cf_mysql.mysql.long_query_time` (time in seconds/microseconds).
+
+### Performance schema ###
+
+The Performance Schema is a feature for monitoring server performance, see related mariadb documentation : [https://mariadb.com/kb/en/library/performance-schema/](https://mariadb.com/kb/en/library/performance-schema/ "https://mariadb.com/kb/en/library/performance-schema/").   
+Performance_schema database, consists of a number of tables that can be queried with regular SQL statements, returning specific performance information.  
+
+To activate Performance_schema, update `cf_mysql.mysql.performance_schema_enabled` property in mysql instance group.  
+
+Performance_schema uses a memory engine (performance_schema) which can potentially increase memory usage when enabled.  
+To see memory used by performance_schema in bytes:
+
+```
+MariaDB [(none)]> show engine performance_schema status;  
++--------------------+--------------------------------------------------------------+-----------+  
+| Type               | Name                                                         |  Status   |  
++--------------------+--------------------------------------------------------------+-----------+  
+...
+| performance_schema | performance_schema.memory                                    | 131117680 |
++--------------------+--------------------------------------------------------------+-----------+ 

jobs/mysql/spec

@@ -256,3 +256,6 @@ properties:
     default: 10
     description: 'Threshold in seconds above which SQL queries get logged in the slow query log file'
 
+  cf_mysql.mysql.performance_schema_enabled:
+    default: false
+    description: "Enables Mariadb Performance Schema when set to true"

jobs/mysql/templates/my.cnf.erb

@@ -202,6 +202,20 @@ ssl_cert                        = /var/vcap/jobs/mysql/certificates/server-cert.
 ssl_key                         = /var/vcap/jobs/mysql/certificates/server-key.pem
 <% end %>
 
+<% if p('cf_mysql.mysql.performance_schema_enabled') %>
+performance_schema              = ON
+# Specifies the maximum number of few instruments to limit memory consumption under 125Mb with 1500 connections
+performance_schema_max_cond_instances   = 1270         #Specifies the maximum number of instrumented condition objects.       (default automated sizing : 2540)
+performance_schema_max_mutex_instances  = 2215         #Specifies the maximum number of instrumented mutex instances.         (default automated sizing : 8860)
+performance_schema_max_rwlock_instances = 1000         #Specifies the maximum number of instrumented rwlock objects.          (default automated sizing : 4620)
+performance_schema_max_socket_instances = 230          #Specifies the maximum number of instrumented socket objects.          (default automated sizing : 640)
+performance_schema_max_table_handles    = 1000         #Specifies the maximum number of opened table objects                  (default automated sizing : 2000)       
+performance_schema_max_table_instances  = 1000         #Specifies the maximum number of instrumented table objects            (default automated sizing : 12500)    
+performance_schema_max_thread_instances = 360          #Specifies how many of the running server threads can be instrumented. (default automated sizing : 720) 
+<% else %>
+performance_schema              = OFF
+<% end %> 
+
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