Help Center > > Developer Guide> SQL Reference> Functions and Operators> Server Signaling Functions

Server Signaling Functions

Updated at:Jul 15, 2020 GMT+08:00

Server signaling functions send control signals to other server processes. Only system administrators can use these functions.

  • pg_cancel_backend(pid int)

    Description: Cancels the current query of a backend.

    Return type: Boolean

    Note: pg_cancel_backend sends a query cancellation (SIGINT) signal to the backend process identified by pid. The PID of an active backend process can be found in the pid column of the pg_stat_activity view, or can be found by listing the database process using ps on the server.

  • pg_rotate_logfile()

    Description: Rotates the log files of the server.

    Return type: Boolean

    Note: pg_rotate_logfile sends a signal to the log file manager, instructing the manager to immediately switch to a new output file. This function works only when redirect_stderr is used for log output. Otherwise, no log file manager subprocess exists.

  • pg_terminate_backend(pid int)

    Description: Terminates a backend thread.

    Return type: Boolean

    Note: Each of these functions returns true if they are successful and false otherwise.

    For example:

     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    SELECT pid from pg_stat_activity;
           pid       
    -----------------
     140657876268816
    (1 rows)
    
    SELECT pg_terminate_backend(140657876268816);
     pg_terminate_backend 
    ----------------------
     t
    (1 row)
    
  • pg_wlm_jump_queue(pid int)

    Description: Moves a task to the top of the CN queue.

    Return type: Boolean

    Note: Each of these functions returns true if they are successful and false otherwise.

  • gs_wlm_switch_cgroup(pid int, cgroup text)

    Description: Moves a job to other Cgroup to improve the job priority.

    Return type: Boolean

    Note: Each of these functions returns true if they are successful and false otherwise.

Did you find this page helpful?

Submit successfully!

Thank you for your feedback. Your feedback helps make our documentation better.

Failed to submit the feedback. Please try again later.

Which of the following issues have you encountered?







Please complete at least one feedback item.

Content most length 200 character

Content is empty.

OK Cancel