_use_adaptive_log_file_sync know more

Configuration Parameters
The following parameters affect the behavior of adaptive log file sync:

  • _use_adaptive_log_file_sync
    • TRUE: Enable adaptive log file sync (default)
    • FALSE: Disable adaptive log file sync (i.e., just use post/wait)
    • POLLING_ONLY: Use polling with adaptive polling interval
  • _adaptive_log_file_sync_use_polling_threshold
    • Larger values make it harder to switch to polling
    • Default value is 110%, which means the current redo synch time must exceed the expected poll time
    • by at least 10% for the algorithm to favor polling over post/wait
    • In the pseudocode above, refer to the use_polling_threshold variable
  • _adaptive_log_file_sync_use_postwait_threshold
    • Smaller values make it harder to switch to post/wait
    • Default value is 50%, which means the current scheduling delay needs to drop to half of that when
    • polling was first used for the algorithm to favor post/wait over polling
    • In the pseudocode above, refer to the use_postwait_threshold variable
  • _adaptive_log_file_sync_poll_aggressiveness
    • Larger values result in smaller polling intervals
    • Default value is 0%, which means none of the current scheduling delay is subtracted from the polling interval
  • _adaptive_log_file_sync_sched_delay_window
    • The window over which the current scheduling delay is computed
    • Default value is 60 seconds, and it is unlikely you need to adjust this
  • _adaptive_log_file_sync_high_switch_freq_threshold
    • A warning is printed if adaptive log file sync switches frequently between post/wait and polling
    • If it is an LRG, a soft assert is also signalled
    • Default threshold is 3 switches per minute
  • _fg_sync_sleep_usecs
    • A non-zero value specified will use polling with a fixed interval and disable adaptive log file sync
  • _log_file_sync_timeout
    • How long the foreground waits for LGWR to post it when post/wait is used
    • Default value is 100 msecs

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