Re: query_id, pg_stat_activity, extended query protocol

> I am also a bit surprised with the choice of using the first Query
> available in the list for the ID, FWIW.


IIUC, the query trees returned from QueryRewrite
will all have the same queryId, so it appears valid to 
use the queryId from the first tree in the list. Right?

Here is an example I was working with that includes user-defined rules
that has a list with more than 1 tree.


postgres=# explain (verbose, generic_plan) insert into mytab values ($1) RETURNING pg_sleep($1), id ;
QUERY PLAN 
-----------------------------------------------------------
Insert on public.mytab (cost=0.00..0.01 rows=1 width=4)
Output: pg_sleep(($1)::double precision), mytab.id
-> Result (cost=0.00..0.01 rows=1 width=4)
Output: $1
Query Identifier: 3703848357297795425


Insert on public.mytab2 (cost=0.00..0.01 rows=0 width=0)
-> Result (cost=0.00..0.01 rows=1 width=4)
Output: $1
Query Identifier: 3703848357297795425


Insert on public.mytab3 (cost=0.00..0.01 rows=0 width=0)
-> Result (cost=0.00..0.01 rows=1 width=4)
Output: $1
Query Identifier: 3703848357297795425


Insert on public.mytab4 (cost=0.00..0.01 rows=0 width=0)
-> Result (cost=0.00..0.01 rows=1 width=4)
Output: $1
Query Identifier: 3703848357297795425
(20 rows)



> Did you consider using \bind to show how this behaves in a regression
> test?


Yes, this is precisely how I tested. Without the patch, I could not
see a queryId after 9 seconds of a pg_sleep, but with the patch it 
appears. See the test below.


## test query
select pg_sleep($1) \bind 30


## unpatched
postgres=# select 
query_id, 
query, 
now()-query_start query_duration, 
state 
from pg_stat_activity where pid <> pg_backend_pid()
and state = 'active';
query_id |        query         | query_duration  | state  
----------+----------------------+-----------------+--------
          | select pg_sleep($1) +| 00:00:08.604845 | active
          | ;                    |                 | 
(1 row)

## patched

postgres=# truncate table large;^C
postgres=# select 
    query_id, 
    query, 
    now()-query_start query_duration, 
    state 
from pg_stat_activity where pid <> pg_backend_pid()
and state = 'active';
      query_id       |        query         | query_duration | state  
---------------------+----------------------+----------------+--------
 2433215470630378210 | select pg_sleep($1) +| 00:00:09.6881  | active
                     | ;                    |                | 
(1 row)


For exec_execute_message, I realized that to report queryId for
Utility and non-utility statements, we need to report the queryId 
inside the portal routines where PlannedStmt contains the queryId.

Attached is the first real attempt at the fix. 

Regards,


Sami