Re: Determine current running query, but no query in pg_stat_activity - Mailing list pgsql-admin

Adam Witney <awitney@sghms.ac.uk> writes:
> I am logged in as the superuser, and I just switched stats_command_string
> on.

Just now?  Too late then --- it needed to be on at the time the other
guy started his query, else he did not send the string to the stats
collector.

> I did find a reference on google to the fact that there was/is a max query
> size length for this?

Yeah, but it truncates, it doesn't just drop the string.

If you are feeling desperate you can attach to the other backend with
gdb:

    $ gdb /path/to/postgres backend-PID
    gdb> print debug_query_string
    gdb> quit
    detach and let process continue? y
    $

            regards, tom lane