WL#10986: REMOVE PERFORMANCE_SCHEMA.SETUP_TIMERS IN 8.0
Affects: Server-8.0 — Status: Complete — Priority: Medium
Remove table performance_schema.setup_timers in 8.0 This feature is over engineered and not used. Removal will allow to reduce the runtime overhead. Related: BUG#71808: Manual does not explain what TICK timer is and why it's different on Windows (this is about performance_timers, not setup_timers, but can be closed if the TICK timer goes away)
Table performance_schema.setup_timers ===================================== This table is removed. Timers used =========== Previously, timers could be configured dynamically (using setup_timers). Now, timers are hard coded as follows: - the WAIT timer uses cycles For platforms where the nanoseconds timer is available: - the IDLE timer uses nanoseconds - the STAGE timer uses nanoseconds - the STATEMENT timer uses nanoseconds - the TRANSACTION timer uses nanoseconds. For platforms where the nanoseconds timer is not available: - the IDLE timer uses microseconds - the STAGE timer uses microseconds - the STATEMENT timer uses microseconds - the TRANSACTION timer uses microseconds. Server startup ============== Upon server startup, the code verifies that assumptions made at build time (aka, hard coding the timers) are correct. In particular: - if a timer is not available, a warning message is printed. Note: printing a warning if timer X is better that timer Y was considered, and then abandoned: it is too unstable in PB2, given that measuring a timer overhead is very unstable under load. Table performance_schema.performance_timers =========================================== The row for the TICK timer is removed.
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