text: -- Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
  --
  -- This program is free software; you can redistribute it and/or modify
  -- it under the terms of the GNU General Public License as published by
  -- the Free Software Foundation; version 2 of the License.
  --
  -- This program is distributed in the hope that it will be useful,
  -- but WITHOUT ANY WARRANTY; without even the implied warranty of
  -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  -- GNU General Public License for more details.
  --
  -- You should have received a copy of the GNU General Public License
  -- along with this program; if not, write to the Free Software
  -- Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  
  --
  -- View: wait_classes_global_by_avg_latency
  -- 
  -- Lists the top wait classes by average latency, ignoring idle (this may be very large).
  --
  -- mysql> select * from wait_classes_global_by_avg_latency where event_class != 'idle';
  -- +-------------------+--------+---------------+-------------+-------------+-------------+
  -- | event_class       | total  | total_latency | min_latency | avg_latency | max_latency |
  -- +-------------------+--------+---------------+-------------+-------------+-------------+
  -- | wait/io/file      | 543123 | 44.60 s       | 19.44 ns    | 82.11 us    | 4.21 s      |
  -- | wait/io/table     |  22002 | 766.60 ms     | 148.72 ns   | 34.84 us    | 44.97 ms    |
  -- | wait/io/socket    |  79613 | 967.17 ms     | 0 ps        | 12.15 us    | 27.10 ms    |
  -- | wait/lock/table   |  35409 | 18.68 ms      | 65.45 ns    | 527.51 ns   | 969.88 us   |
  -- | wait/synch/rwlock |  37935 | 4.61 ms       | 21.38 ns    | 121.61 ns   | 34.65 us    |
  -- | wait/synch/mutex  | 390622 | 18.60 ms      | 19.44 ns    | 47.61 ns    | 10.32 us    |
  -- +-------------------+--------+---------------+-------------+-------------+-------------+
  --
  
  CREATE OR REPLACE
    ALGORITHM = TEMPTABLE
    DEFINER = 'mysql.sys'@'localhost'
    SQL SECURITY INVOKER 
  VIEW wait_classes_global_by_avg_latency (
    event_class,
    total,
    total_latency,
    min_latency,
    avg_latency,
    max_latency
  ) AS
  SELECT SUBSTRING_INDEX(event_name,'/', 3) AS event_class,
         SUM(COUNT_STAR) AS total,
         format_pico_time(CAST(SUM(sum_timer_wait) AS UNSIGNED)) AS total_latency,
         format_pico_time(MIN(min_timer_wait)) AS min_latency,
         format_pico_time(IFNULL(SUM(sum_timer_wait) / NULLIF(SUM(COUNT_STAR), 0), 0)) AS avg_latency,
         format_pico_time(CAST(MAX(max_timer_wait) AS UNSIGNED)) AS max_latency
    FROM performance_schema.events_waits_summary_global_by_event_name
   WHERE sum_timer_wait > 0
     AND event_name != 'idle'
   GROUP BY event_class
   ORDER BY IFNULL(SUM(sum_timer_wait) / NULLIF(SUM(COUNT_STAR), 0), 0) DESC;
  