Re: RFC: Logging plan of the running query

On 2023-09-25 18:49, Andrey Lepikhov wrote:
> On 25/9/2023 14:21, torikoshia wrote:
>> On 2023-09-20 14:39, Lepikhov Andrei wrote:
>> Hmm, as a test, I made sure to call ProcessLogQueryPlanInterrupt() on 
>> all CFI using 
>> v28-0002-Testing-attempt-logging-plan-on-ever-CFI-call.patch, and then 
>> ran the following query but did not cause any problems.
>> 
>> ```
>> =# CREATE TABLE test();
>> =# CREATE OR REPLACE FUNCTION ddl() RETURNS void AS $$
>> BEGIN
>>    EXECUTE format('ALTER TABLE test ADD COLUMN x integer;');
>>    PERFORM pg_sleep(5);
>> END; $$ LANGUAGE plpgsql VOLATILE;
>> =# SELECT ddl();
>> ```
>> 
>> Is this the case you're worrying about?
> 
> I didn't find a problem either. I just feel uncomfortable if, at the
> moment of interruption, we have a descriptor of another query than the
> query have been executing and holding resources.

I think that "descriptor" here refers to ActiveQueryDesc, in which case
it is updated at the beginning of ExecutorRun(), so I am wondering if
the situation you're worried about would not occur.

---------
@@ -303,10 +306,21 @@ ExecutorRun(QueryDesc *queryDesc,
             ScanDirection direction, uint64 count,
             bool execute_once)
  {
+   /*
+    * Update ActiveQueryDesc here to enable retrieval of the currently
+    * running queryDesc for nested queries.
+    */
+   QueryDesc *save_ActiveQueryDesc;
+
+   save_ActiveQueryDesc = ActiveQueryDesc;
+   ActiveQueryDesc = queryDesc;
---------
-- 
Regards,

--
Atsushi Torikoshi
NTT DATA Group Corporation