TODO

TODO LIST
=========

0. record the collection time
1. compare metrics (percentage variation etc)
2. add the other missing metrics which are in the digest table
3. get the errors and warnings from 

root@localhost [performance_schema]> select * from events_statements_current   limit 1\G
*************************** 1. row ***************************
              THREAD_ID: 33
               EVENT_ID: 593
           END_EVENT_ID: NULL
             EVENT_NAME: statement/sql/select
                 SOURCE: socket_connection.cc:98
            TIMER_START: 169478783373902000
              TIMER_END: 169478791353084000
             TIMER_WAIT: 7979182000
              LOCK_TIME: 177000000
               SQL_TEXT: select * from events_statements_current   limit 1
                 DIGEST: NULL <==========
            DIGEST_TEXT: NULL
         CURRENT_SCHEMA: performance_schema 
            OBJECT_TYPE: NULL
          OBJECT_SCHEMA: NULL <=======
            OBJECT_NAME: NULL
  OBJECT_INSTANCE_BEGIN: NULL
            MYSQL_ERRNO: 0    <========
      RETURNED_SQLSTATE: NULL <========
           MESSAGE_TEXT: NULL <========
                 ERRORS: 0
               WARNINGS: 0
          ROWS_AFFECTED: 0
              ROWS_SENT: 0
          ROWS_EXAMINED: 0
CREATED_TMP_DISK_TABLES: 0
     CREATED_TMP_TABLES: 0
       SELECT_FULL_JOIN: 0
 SELECT_FULL_RANGE_JOIN: 0
           SELECT_RANGE: 0
     SELECT_RANGE_CHECK: 0
            SELECT_SCAN: 1
      SORT_MERGE_PASSES: 0
             SORT_RANGE: 0
              SORT_ROWS: 0
              SORT_SCAN: 0
          NO_INDEX_USED: 1
     NO_GOOD_INDEX_USED: 0
       NESTING_EVENT_ID: NULL
     NESTING_EVENT_TYPE: NULL
    NESTING_EVENT_LEVEL: 0
1 row in set (0.01 sec)

or use history table(s)

so need to collect the DIGEST and match against that.