Documentation Home
MySQL 5.7 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 35.6Mb
PDF (A4) - 35.6Mb
PDF (RPM) - 34.6Mb
EPUB - 8.7Mb
HTML Download (TGZ) - 8.4Mb
HTML Download (Zip) - 8.5Mb
HTML Download (RPM) - 7.3Mb
Eclipse Doc Plugin (TGZ) - 9.3Mb
Eclipse Doc Plugin (Zip) - 11.4Mb
Man Pages (TGZ) - 202.2Kb
Man Pages (Zip) - 307.6Kb
Info (Gzip) - 3.3Mb
Info (Zip) - 3.3Mb
Excerpts from this Manual The performance_timers Table

The performance_timers table shows which event timers are available:

mysql> SELECT * FROM performance_timers;
| CYCLE       |      2389029850 |                1 |             72 |
| NANOSECOND  |      1000000000 |                1 |            112 |
| MICROSECOND |         1000000 |                1 |            136 |
| MILLISECOND |            1036 |                1 |            168 |
| TICK        |             105 |                1 |           2416 |

The timers in setup_timers that you can use are those that do not have NULL in the other columns. If the values associated with a given timer name are NULL, that timer is not supported on your platform.

The performance_timers table has these columns:


    The name by which to refer to the timer when configuring the setup_timers table.


    The number of timer units per second. For a cycle timer, the frequency is generally related to the CPU speed. For example, on a system with a 2.4GHz processor, the CYCLE may be close to 2400000000.


    Indicates the number of timer units by which timer values increase. If a timer has a resolution of 10, its value increases by 10 each time.


    The minimal number of cycles of overhead to obtain one timing with the given timer. The Performance Schema determines this value by invoking the timer 20 times during initialization and picking the smallest value. The total overhead really is twice this amount because the instrumentation invokes the timer at the start and end of each event. The timer code is called only for timed events, so this overhead does not apply for nontimed events.

TRUNCATE TABLE is not permitted for the performance_timers table.

User Comments
Sign Up Login You must be logged in to post a comment.