On Mon, Aug 5, 2024 at 3:19 PM Anthonin Bonnefoy
<anthonin.bonne...@datadoghq.com> wrote:
>
> I've realised my initial approach was wrong, calling the post parse
> for all nested queries in analyze.c prevents extension like pgss to
> correctly track the query's nesting level.
>
> I've changed the approach to replicate what's done in ExplainQuery to
> both CreateTableAs and DeclareCursor: Jumble the query contained by
> the utility statement and call the post parse hook before it is
> planned or executed. Additionally, explain's nested query can itself
> be a CreateTableAs or DeclareCursor which also needs to be jumbled.
> The issue is visible when explaining a CreateTableAs or DeclareCursor
> Query, the queryId is missing despite the verbose.
>
> EXPLAIN (verbose) create table test_t as select 1;
> QUERY PLAN
> ------------------------------------------
> Result (cost=0.00..0.01 rows=1 width=4)
> Output: 1
>
> Post patch, the query id is correctly displayed.
>
> EXPLAIN (verbose) create table test_t as select 1;
> QUERY PLAN
> ------------------------------------------
> Result (cost=0.00..0.01 rows=1 width=4)
> Output: 1
> Query Identifier: 2800308901962295548
>
play with pg_stat_statements. settings:
name | setting
-----------------------------------+---------
pg_stat_statements.max | 5000
pg_stat_statements.save | on
pg_stat_statements.track | all
pg_stat_statements.track_planning | on
pg_stat_statements.track_utility | on
SELECT pg_stat_statements_reset();
select 1;
select 2;
SELECT queryid, left(query, 60),plans, calls, rows FROM
pg_stat_statements ORDER BY calls DESC LIMIT 5;
returns:
queryid | left
| plans | calls | rows
----------------------+--------------------------------------------------------------+-------+-------+------
2800308901962295548 | select $1
| 2 | 2 | 2
The output is what we expect.
now after applying your patch.
SELECT pg_stat_statements_reset();
EXPLAIN (verbose) create table test_t as select 1;
EXPLAIN (verbose) create table test_t as select 2;
SELECT queryid, left(query, 60),plans, calls, rows FROM
pg_stat_statements ORDER BY calls DESC LIMIT 5;
the output is:
queryid | left
| plans | calls | rows
----------------------+--------------------------------------------------------------+-------+-------+------
2800308901962295548 | EXPLAIN (verbose) create table test_t as
select 1; | 2 | 2 | 0
2093602470903273926 | EXPLAIN (verbose) create table test_t as
select $1 | 0 | 2 | 0
-2694081619397734273 | SELECT pg_stat_statements_reset()
| 0 | 1 | 1
2643570658797872815 | SELECT queryid, left(query, $1),plans, calls,
rows FROM pg_s | 1 | 0 | 0
"EXPLAIN (verbose) create table test_t as select 1;" called twice,
is that what we expect?
should first row, the normalized query becomes
EXPLAIN (verbose) create table test_t as select $1;
?
