Re: query_id, pg_stat_activity, extended query protocol

[Imseih (AWS), Sami]

> FWIW, I'd like to think that we could improve the situation, requiring
> a mix of calling pgstat_report_query_id() while feeding on some query
> IDs retrieved from CachedPlanSource->query_list. I have not in
> details looked at how much could be achieved, TBH.

I was dealing with this today and found this thread. I spent some time
looking at possible solutions.

In the flow of extended query protocol, the exec_parse_message 
reports the queryId, but subsequent calls to exec_bind_message
and exec_execute_message reset the queryId when calling
pgstat_report_activity(STATE_RUNNING,..) as you can see below.
  
     /*
      * If a new query is started, we reset the query identifier as it'll only
      * be known after parse analysis, to avoid reporting last query's
      * identifier.
      */
     if (state == STATE_RUNNING)
         beentry->st_query_id = UINT64CONST(0);


So, I think the simple answer is something like the below. 
Inside exec_bind_message and exec_execute_message,
the query_id should be reported after pg_report_activity. 

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 76f48b13d2..7ec2df91d5 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -1678,6 +1678,7 @@ exec_bind_message(StringInfo input_message)
        debug_query_string = psrc->query_string;
 
        pgstat_report_activity(STATE_RUNNING, psrc->query_string);
+       pgstat_report_query_id(linitial_node(Query, psrc->query_list)->queryId, 
true);
 
        set_ps_display("BIND");
 
@@ -2146,6 +2147,7 @@ exec_execute_message(const char *portal_name, long 
max_rows)
        debug_query_string = sourceText;
 
        pgstat_report_activity(STATE_RUNNING, sourceText);
+       pgstat_report_query_id(portal->queryDesc->plannedstmt->queryId, true);
 
        cmdtagname = GetCommandTagNameAndLen(portal->commandTag, &cmdtaglen);


thoughts?


Regards,

Sami Imseih
Amazon Web Services (AWS)