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postgres/contrib/pg_stat_statements/expected/level_tracking.out
Michael Paquier dc68515968 Show values of SET statements as constants in pg_stat_statements 
This is a continuation of work like 11c34b342bd7, done to reduce the
bloat of pg_stat_statements by applying more normalization to query
entries.  This commit is able to detect and normalize values in
VariableSetStmt, resulting in:
SET conf_param = $1

Compared to other parse nodes, VariableSetStmt is embedded in much more
places in the parser, impacting many query patterns in
pg_stat_statements.  A custom jumble function is used, with an extra
field in the node to decide if arguments should be included in the
jumbling or not, a location field being not enough for this purpose.
This approach allows for a finer tuning.

Clauses relying on one or more keywords are not normalized, for example:
* DEFAULT
* FROM CURRENT
* List of keywords.  SET SESSION CHARACTERISTICS AS TRANSACTION,
where it is critical to differentiate different sets of options, is a
good example of why normalization should not happen.

Some queries use VariableSetStmt for some subclauses with SET, that also
have their values normalized:
- ALTER DATABASE
- ALTER ROLE
- ALTER SYSTEM
- CREATE/ALTER FUNCTION

ba90eac7a995 has added test coverage for most of the existing SET
patterns.  The expected output of these tests shows the difference this
commit creates.  Normalization could be perhaps applied to more portions
of the grammar but what is done here is conservative, and good enough as
a starting point.

Author: Greg Sabino Mullane, Michael Paquier
Discussion: https://postgr.es/m/36e5bffe-e989-194f-85c8-06e7bc88e6f7@amazon.com
Discussion: https://postgr.es/m/B44FA29D-EBD0-4DD9-ABC2-16F1CB087074@amazon.com
Discussion: https://postgr.es/m/CAKAnmmJtJY2jzQN91=2QAD2eAJAA-Per61eyO48-TyxEg-q0Rg@mail.gmail.com
2024-09-30 14:02:00 +09:00

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--
-- Statement level tracking
--
SET pg_stat_statements.track_utility = TRUE;
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
-- DO block - top-level tracking.
CREATE TABLE stats_track_tab (x int);
SET pg_stat_statements.track = 'top';
DELETE FROM stats_track_tab;
DO $$
BEGIN
DELETE FROM stats_track_tab;
END;
$$ LANGUAGE plpgsql;
SELECT toplevel, calls, query FROM pg_stat_statements
WHERE query LIKE '%DELETE%' ORDER BY query COLLATE "C", toplevel;
toplevel | calls | query
----------+-------+--------------------------------
t | 1 | DELETE FROM stats_track_tab
t | 1 | DO $$ +
| | BEGIN +
| | DELETE FROM stats_track_tab;+
| | END; +
| | $$ LANGUAGE plpgsql
(2 rows)
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
-- DO block - all-level tracking.
SET pg_stat_statements.track = 'all';
DELETE FROM stats_track_tab;
DO $$
BEGIN
DELETE FROM stats_track_tab;
END; $$;
DO LANGUAGE plpgsql $$
BEGIN
-- this is a SELECT
PERFORM 'hello world'::TEXT;
END; $$;
SELECT toplevel, calls, query FROM pg_stat_statements
ORDER BY query COLLATE "C", toplevel;
toplevel | calls | query
----------+-------+----------------------------------------------------
f | 1 | DELETE FROM stats_track_tab
t | 1 | DELETE FROM stats_track_tab
t | 1 | DO $$ +
| | BEGIN +
| | DELETE FROM stats_track_tab; +
| | END; $$
t | 1 | DO LANGUAGE plpgsql $$ +
| | BEGIN +
| | -- this is a SELECT +
| | PERFORM 'hello world'::TEXT; +
| | END; $$
f | 1 | SELECT $1::TEXT
t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
t | 1 | SET pg_stat_statements.track = $1
(7 rows)
-- Procedure with multiple utility statements.
CREATE OR REPLACE PROCEDURE proc_with_utility_stmt()
LANGUAGE SQL
AS $$
SHOW pg_stat_statements.track;
show pg_stat_statements.track;
SHOW pg_stat_statements.track_utility;
$$;
SET pg_stat_statements.track_utility = TRUE;
-- all-level tracking.
SET pg_stat_statements.track = 'all';
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
CALL proc_with_utility_stmt();
SELECT toplevel, calls, query FROM pg_stat_statements
ORDER BY query COLLATE "C", toplevel;
toplevel | calls | query
----------+-------+----------------------------------------------------
t | 1 | CALL proc_with_utility_stmt()
t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
f | 2 | SHOW pg_stat_statements.track
f | 1 | SHOW pg_stat_statements.track_utility
(4 rows)
-- top-level tracking.
SET pg_stat_statements.track = 'top';
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
CALL proc_with_utility_stmt();
SELECT toplevel, calls, query FROM pg_stat_statements
ORDER BY query COLLATE "C", toplevel;
toplevel | calls | query
----------+-------+----------------------------------------------------
t | 1 | CALL proc_with_utility_stmt()
t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(2 rows)
-- DO block - top-level tracking without utility.
SET pg_stat_statements.track = 'top';
SET pg_stat_statements.track_utility = FALSE;
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
DELETE FROM stats_track_tab;
DO $$
BEGIN
DELETE FROM stats_track_tab;
END; $$;
DO LANGUAGE plpgsql $$
BEGIN
-- this is a SELECT
PERFORM 'hello world'::TEXT;
END; $$;
SELECT toplevel, calls, query FROM pg_stat_statements
ORDER BY query COLLATE "C", toplevel;
toplevel | calls | query
----------+-------+----------------------------------------------------
t | 1 | DELETE FROM stats_track_tab
t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(2 rows)
-- DO block - all-level tracking without utility.
SET pg_stat_statements.track = 'all';
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
DELETE FROM stats_track_tab;
DO $$
BEGIN
DELETE FROM stats_track_tab;
END; $$;
DO LANGUAGE plpgsql $$
BEGIN
-- this is a SELECT
PERFORM 'hello world'::TEXT;
END; $$;
SELECT toplevel, calls, query FROM pg_stat_statements
ORDER BY query COLLATE "C", toplevel;
toplevel | calls | query
----------+-------+----------------------------------------------------
f | 1 | DELETE FROM stats_track_tab
t | 1 | DELETE FROM stats_track_tab
f | 1 | SELECT $1::TEXT
t | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(4 rows)
-- PL/pgSQL function - top-level tracking.
SET pg_stat_statements.track = 'top';
SET pg_stat_statements.track_utility = FALSE;
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
CREATE FUNCTION PLUS_TWO(i INTEGER) RETURNS INTEGER AS $$
DECLARE
r INTEGER;
BEGIN
SELECT (i + 1 + 1.0)::INTEGER INTO r;
RETURN r;
END; $$ LANGUAGE plpgsql;
SELECT PLUS_TWO(3);
plus_two
----------
5
(1 row)
SELECT PLUS_TWO(7);
plus_two
----------
9
(1 row)
-- SQL function --- use LIMIT to keep it from being inlined
CREATE FUNCTION PLUS_ONE(i INTEGER) RETURNS INTEGER AS
$$ SELECT (i + 1.0)::INTEGER LIMIT 1 $$ LANGUAGE SQL;
SELECT PLUS_ONE(8);
plus_one
----------
9
(1 row)
SELECT PLUS_ONE(10);
plus_one
----------
11
(1 row)
SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
calls | rows | query
-------+------+----------------------------------------------------
2 | 2 | SELECT PLUS_ONE($1)
2 | 2 | SELECT PLUS_TWO($1)
1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(3 rows)
-- immutable SQL function --- can be executed at plan time
CREATE FUNCTION PLUS_THREE(i INTEGER) RETURNS INTEGER AS
$$ SELECT i + 3 LIMIT 1 $$ IMMUTABLE LANGUAGE SQL;
SELECT PLUS_THREE(8);
plus_three
------------
11
(1 row)
SELECT PLUS_THREE(10);
plus_three
------------
13
(1 row)
SELECT toplevel, calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
toplevel | calls | rows | query
----------+-------+------+------------------------------------------------------------------------------
t | 2 | 2 | SELECT PLUS_ONE($1)
t | 2 | 2 | SELECT PLUS_THREE($1)
t | 2 | 2 | SELECT PLUS_TWO($1)
t | 1 | 3 | SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"
t | 1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(5 rows)
-- PL/pgSQL function - all-level tracking.
SET pg_stat_statements.track = 'all';
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
-- we drop and recreate the functions to avoid any caching funnies
DROP FUNCTION PLUS_ONE(INTEGER);
DROP FUNCTION PLUS_TWO(INTEGER);
DROP FUNCTION PLUS_THREE(INTEGER);
-- PL/pgSQL function
CREATE FUNCTION PLUS_TWO(i INTEGER) RETURNS INTEGER AS $$
DECLARE
r INTEGER;
BEGIN
SELECT (i + 1 + 1.0)::INTEGER INTO r;
RETURN r;
END; $$ LANGUAGE plpgsql;
SELECT PLUS_TWO(-1);
plus_two
----------
1
(1 row)
SELECT PLUS_TWO(2);
plus_two
----------
4
(1 row)
-- SQL function --- use LIMIT to keep it from being inlined
CREATE FUNCTION PLUS_ONE(i INTEGER) RETURNS INTEGER AS
$$ SELECT (i + 1.0)::INTEGER LIMIT 1 $$ LANGUAGE SQL;
SELECT PLUS_ONE(3);
plus_one
----------
4
(1 row)
SELECT PLUS_ONE(1);
plus_one
----------
2
(1 row)
SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
calls | rows | query
-------+------+----------------------------------------------------
2 | 2 | SELECT (i + $2 + $3)::INTEGER
2 | 2 | SELECT (i + $2)::INTEGER LIMIT $3
2 | 2 | SELECT PLUS_ONE($1)
2 | 2 | SELECT PLUS_TWO($1)
1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(5 rows)
-- immutable SQL function --- can be executed at plan time
CREATE FUNCTION PLUS_THREE(i INTEGER) RETURNS INTEGER AS
$$ SELECT i + 3 LIMIT 1 $$ IMMUTABLE LANGUAGE SQL;
SELECT PLUS_THREE(8);
plus_three
------------
11
(1 row)
SELECT PLUS_THREE(10);
plus_three
------------
13
(1 row)
SELECT toplevel, calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
toplevel | calls | rows | query
----------+-------+------+------------------------------------------------------------------------------
f | 2 | 2 | SELECT (i + $2 + $3)::INTEGER
f | 2 | 2 | SELECT (i + $2)::INTEGER LIMIT $3
t | 2 | 2 | SELECT PLUS_ONE($1)
t | 2 | 2 | SELECT PLUS_THREE($1)
t | 2 | 2 | SELECT PLUS_TWO($1)
t | 1 | 5 | SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C"
f | 2 | 2 | SELECT i + $2 LIMIT $3
t | 1 | 1 | SELECT pg_stat_statements_reset() IS NOT NULL AS t
(8 rows)
--
-- pg_stat_statements.track = none
--
SET pg_stat_statements.track = 'none';
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
SELECT 1 AS "one";
one
-----
1
(1 row)
SELECT 1 + 1 AS "two";
two
-----
2
(1 row)
SELECT calls, rows, query FROM pg_stat_statements ORDER BY query COLLATE "C";
calls | rows | query
-------+------+-------
(0 rows)
SELECT pg_stat_statements_reset() IS NOT NULL AS t;
t
---
t
(1 row)
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