Re: Add “FOR UPDATE NOWAIT” lock details to the log.

On 2024/10/18 19:07, Seino Yuki wrote:
>> The choice between adding a new GUC or extending the existing one
>> (e.g., log_lock_waits)
>> is debatable, but I prefer the latter. I'm considering extending log_lock_waits
>> to accept a value like "fail". If set to "on" (the current behavior),
>> detailed logs are generated when the lock wait time exceeds deadlock_timeout.
>> If set to "fail", logs are generated whenever a lock wait fails. If both are
>> specified, logs would be triggered when the wait time exceeds
>> deadlock_timeout or
>> when a lock wait fails.
> 
> Thanks for the idea.
> Changed log_lock_waits to an enum type and added fail and all.
> "off"  : No log message(default).
> "on"   : If over deadlock_timeout(the current behavior).
> "fail" : If lock failed.
> "all"  : All pettern.

I'm still thinking about how we should handle logging for lock failures
caused by the nowait option. Extending the existing log_lock_waits parameter
has the advantage of avoiding a new GUC, but it might make configuration
more complicated. I'm starting to think adding a new GUC might be a better option.

Regarding the patch, when I applied it to HEAD, it failed to compile with
the following errors. Could you update the patch to address this?

proc.c:1538:20: error: use of undeclared identifier 'buf'
  1538 |                         initStringInfo(&buf);
       |                                         ^
proc.c:1539:20: error: use of undeclared identifier 'lock_waiters_sbuf'
  1539 |                         initStringInfo(&lock_waiters_sbuf);
       |                                         ^
proc.c:1540:20: error: use of undeclared identifier 'lock_holders_sbuf'
  1540 |                         initStringInfo(&lock_holders_sbuf);
       |                                         ^
....


Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION