---------------------------------------------------------------
--- REPRO STEPS
---------------------------------------------------------------
drop table if exists t1 ; create table t1 ( id int );

CREATE OR REPLACE FUNCTION test_prep2() RETURNS void AS $$
        DECLARE
          lid int;
        BEGIN
                SELECT * FROM t1 INTO lid;
        END;
$$ LANGUAGE plpgsql;

select test_prep();
select test_prep2();
select test_prep2();
select test_prep2();

drop table if exists t1 ; create table t1 ( id int );
select test_prep2();


------------------
--- RESULTS
------------------

The first time "select query, query_id from pg_stat_activity ;" is ran,
we see the correct query_id of the top-level "select test_prep2();"

postgres=# select query, query_id from pg_stat_activity ;
                     query                      |       query_id       
------------------------------------------------+----------------------
 select query, query_id from pg_stat_activity ; |  4920466282180912204
 select test_prep2();                           | -8872343059522300094
                                                |                     
                                                |                     
                                                |                     
                                                |                     
                                                |                     
(7 rows)

postgres=# explain verbose select test_prep2();
                QUERY PLAN                
------------------------------------------
 Result  (cost=0.00..0.26 rows=1 width=4)
   Output: test_prep2()
 Query Identifier: -8872343059522300094
(3 rows)


but after the table is dropped and recreated, the advertised
query_id is wrong for the query text. It is the query_id of
"select * from t1;"



postgres=# select query, query_id from pg_stat_activity ;
                     query                      |       query_id       
------------------------------------------------+----------------------
 select query, query_id from pg_stat_activity ; |  4920466282180912204
 select test_prep2();                           | -6535803560158626277
                                                |                     
                                                |                     
                                                |                     
                                                |                     
                                                |                     
(7 rows)


postgres=# explain verbose select * from t1;
                         QUERY PLAN                          
-------------------------------------------------------------
 Seq Scan on public.t1  (cost=0.00..35.50 rows=2550 width=4)
   Output: id
 Query Identifier: -6535803560158626277
(3 rows)