Re: RFC: Logging plan of the running query

On 2023-10-27 16:06, Étienne BERSAC wrote:
> Hi Torikoshia,
>
>> If so, we once tried to implement such function for getting memory
>> contexts.
>> However, this attempt didn't succeed because it could lead dead lock
>> situation[1].
>
> Thanks for the pointer. Why not use client log message to allow client
> to get plan without locking backend memory context and without access
> to server log ? I missed the rationnal for not sending the plan to
> client.

If we use client log message, that message is shown on the target
process whose pid is specified by the parameter of pg_log_query_plan():

(pid:1000)=# select pg_sleep(60);
(pid:1001)=# select pg_log_query_plan(1000);
(pid:1000)=# LOG: query plan running on backend with PID 1000 is:
Query Text: select pg_sleep(1000);
Result (cost=0.00..0.01 rows=1 width=4)
Output: pg_sleep('1000'::double precision)

I think this is not an expected behavior and we set elevel to
LOG_SERVER_ONLY.

--
Regards,

--
Atsushi Torikoshi
NTT DATA Group Corporation