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Fix some problems found during underwent of the AQO by Join-Order-Benchmark:
1. Minor code improvements 2. Introduce the show_cardinality_errors(bool) routine that can show cardinality errors detected by the AQO that made during last execution under or without AQO control. 3. Ignore queries that don't touch any database relations.
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8 files changed

+137
-89
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‎aqo--1.3--1.4.sql‎

Lines changed: 48 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -5,31 +5,60 @@
55

66
ALTER TABLE public.aqo_data ADD COLUMN reliability double precision [];
77

8+
DROP FUNCTION public.top_error_queries(int);
9+
10+
--
11+
-- Get cardinality error of queries the last time they were executed.
12+
-- IN:
13+
-- controlled - show queries executed under a control of AQO (true);
14+
-- executed without an AQO control, but AQO has a stat on the query (false).
815
--
9-
-- Get IDs of queries having the largest cardinality error when last executed.
16+
-- OUT:
1017
-- num - sequental number. Smaller number corresponds to higher error.
11-
-- qhash - ID of a query.
12-
-- error - AQO error calculated over plan nodes of the query.
18+
-- id - ID of a query.
19+
-- fshash - feature space. Usually equal to zero or ID.
20+
-- error - AQO error that calculated on plan nodes of the query.
21+
-- nexecs - number of executions of queries associated with this ID.
1322
--
14-
CREATE OR REPLACE FUNCTION public.show_cardinality_errors()
15-
RETURNS TABLE(num bigint, id bigint, error float)
23+
CREATE OR REPLACE FUNCTION public.show_cardinality_errors(controlled boolean)
24+
RETURNS TABLE(num bigint, id bigint, fshash bigint, error float, nexecs bigint)
1625
AS $$
1726
BEGIN
27+
IF (controlled) THEN
28+
RETURN QUERY
29+
SELECT
30+
row_number() OVER (ORDER BY (cerror, query_id, fs_hash) DESC) AS nn,
31+
query_id, fs_hash, cerror, execs
32+
FROM (
33+
SELECT
34+
aq.query_hash AS query_id,
35+
aq.fspace_hash AS fs_hash,
36+
cardinality_error_with_aqo[array_length(cardinality_error_with_aqo, 1)] AS cerror,
37+
executions_with_aqo AS execs
38+
FROM public.aqo_queries aq JOIN public.aqo_query_stat aqs
39+
ON aq.query_hash = aqs.query_hash
40+
WHERE TRUE = ANY (SELECT unnest(cardinality_error_with_aqo) IS NOT NULL)
41+
) AS q1
42+
ORDER BY nn ASC;
43+
ELSE
1844
RETURN QUERY
19-
SELECT
20-
row_number() OVER (ORDER BY (cerror, qhash) DESC) AS nn,
21-
qhash, cerror
22-
FROM (
23-
SELECT
24-
aq.query_hash AS qhash,
25-
cardinality_error_with_aqo[array_length(cardinality_error_with_aqo, 1)] AS cerror
26-
FROM public.aqo_queries aq JOIN public.aqo_query_stat aqs
27-
ON aq.query_hash = aqs.query_hash
28-
WHERE TRUE = ANY (SELECT unnest(cardinality_error_with_aqo) IS NOT NULL)
29-
) AS q1
30-
ORDER BY nn ASC;
45+
SELECT
46+
row_number() OVER (ORDER BY (cerror, query_id, fs_hash) DESC) AS nn,
47+
query_id, fs_hash, cerror, execs
48+
FROM (
49+
SELECT
50+
aq.query_hash AS query_id,
51+
aq.fspace_hash AS fs_hash,
52+
array_avg(cardinality_error_without_aqo) AS cerror,
53+
executions_without_aqo AS execs
54+
FROM public.aqo_queries aq JOIN public.aqo_query_stat aqs
55+
ON aq.query_hash = aqs.query_hash
56+
WHERE TRUE = ANY (SELECT unnest(cardinality_error_without_aqo) IS NOT NULL)
57+
) AS q1
58+
ORDER BY (nn) ASC;
59+
END IF;
3160
END;
3261
$$ LANGUAGE plpgsql;
3362

34-
COMMENT ON FUNCTION public.show_cardinality_errors() IS
35-
'Get cardinality error of last query execution. Return queries having the largest error.';
63+
COMMENT ON FUNCTION public.show_cardinality_errors(boolean) IS
64+
'Get cardinality error of queries the last time they were executed. Order queries according to an error value.';

‎expected/gucs.out‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -30,9 +30,9 @@ EXPLAIN (ANALYZE, VERBOSE, COSTS OFF, TIMING OFF, SUMMARY OFF)
3030

3131
-- Check existence of the interface functions.
3232
SELECT obj_description('public.show_cardinality_errors'::regproc::oid);
33-
obj_description
34-
-----------------------------------------------------------------------------------------
35-
Get cardinality error of last query execution. Return queries having the largest error.
33+
obj_description
34+
---------------------------------------------------------------------------------------------------------------
35+
Get cardinality error of queries the last time they were executed. Order queries according to an error value.
3636
(1 row)
3737

3838
DROP EXTENSION aqo;

‎expected/top_queries.out‎

Lines changed: 37 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -2,23 +2,31 @@ CREATE EXTENSION aqo;
22
SET aqo.mode = 'disabled';
33
SET aqo.force_collect_stat = 'on';
44
--
5-
-- num of generate_series(1,1000000) query should be the first
5+
-- Dummy test. CREATE TABLE shouldn't find in the ML storage. But a simple
6+
-- select must be in. Also here we test on gathering a stat on temp and plain
7+
-- relations.
68
--
7-
SELECT count(*) FROM generate_series(1,1000000);
8-
count
9-
---------
10-
1000000
9+
CREATE TEMP TABLE ttt AS SELECT count(*) AS cnt FROM generate_series(1,10);
10+
CREATE TABLE ttp AS SELECT count(*) AS cnt FROM generate_series(1,10);
11+
SELECT count(*) AS cnt FROM ttt WHERE cnt % 100 = 0;
12+
cnt
13+
-----
14+
0
15+
(1 row)
16+
17+
SELECT count(*) AS cnt FROM ttp WHERE cnt % 100 = 0;
18+
cnt
19+
-----
20+
0
1121
(1 row)
1222

13-
SELECT num FROM top_time_queries(10) AS tt WHERE
14-
tt.fspace_hash = (SELECT fspace_hash FROM aqo_queries WHERE
15-
aqo_queries.query_hash = (SELECT aqo_query_texts.query_hash FROM aqo_query_texts
16-
WHERE query_text = 'SELECT count(*) FROM generate_series(1,1000000);'));
17-
NOTICE: Top 10 execution time queries
23+
SELECT num FROM top_time_queries(3);
24+
NOTICE: Top 3 execution time queries
1825
num
1926
-----
2027
1
21-
(1 row)
28+
2
29+
(2 rows)
2230

2331
--
2432
-- num of query uses table t2 should be bigger than num of query uses table t1 and be the first
@@ -39,13 +47,23 @@ SELECT count(*) FROM (SELECT x, y FROM t2 GROUP BY GROUPING SETS ((x,y), (x), (y
3947
31
4048
(1 row)
4149

42-
SELECT num FROM top_error_queries(10) AS te WHERE
43-
te.fspace_hash = (SELECT fspace_hash FROM aqo_queries WHERE
44-
aqo_queries.query_hash = (SELECT aqo_query_texts.query_hash FROM aqo_query_texts
45-
WHERE query_text = 'SELECT count(*) FROM (SELECT x, y FROM t2 GROUP BY GROUPING SETS ((x,y), (x), (y), ())) AS q1;'));
46-
NOTICE: Top 10 cardinality error queries
47-
num
48-
-----
49-
1
50+
SELECT num, to_char(error, '9.99EEEE') FROM show_cardinality_errors(false) AS te
51+
WHERE te.fshash = (
52+
SELECT fspace_hash FROM aqo_queries
53+
WHERE aqo_queries.query_hash = (
54+
SELECT aqo_query_texts.query_hash FROM aqo_query_texts
55+
WHERE query_text = 'SELECT count(*) FROM (SELECT x, y FROM t2 GROUP BY GROUPING SETS ((x,y), (x), (y), ())) AS q1;'
56+
)
57+
);
58+
num | to_char
59+
-----+-----------
60+
1 | 1.94e+00
61+
(1 row)
62+
63+
-- Should return zero
64+
SELECT count(*) FROM show_cardinality_errors(true);
65+
count
66+
-------
67+
0
5068
(1 row)
5169

‎expected/unsupported.out‎

Lines changed: 9 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -543,17 +543,16 @@ EXPLAIN (COSTS OFF)
543543
SELECT
544544
num,
545545
to_char(error, '9.99EEEE')::text AS error
546-
FROM public.show_cardinality_errors()
546+
FROM public.show_cardinality_errors(true)
547547
WHERE error > 0.;
548548
num | error
549549
-----+-----------
550-
1 | 9.69e+02
551-
2 | 1.15e+02
550+
1 | 1.15e+02
551+
2 | 3.00e+01
552552
3 | 3.00e+01
553553
4 | 3.00e+01
554-
5 | 3.00e+01
555-
6 | 1.33e+00
556-
(6 rows)
554+
5 | 1.33e+00
555+
(5 rows)
557556

558557
DROP TABLE t,t1 CASCADE;
559558
SELECT public.clean_aqo_data();
@@ -565,27 +564,10 @@ NOTICE: Cleaning aqo_data records
565564

566565
-- TODO: figure out with remaining queries in the ML storage.
567566
SELECT num, to_char(error, '9.99EEEE')::text AS error, query_text
568-
FROM public.show_cardinality_errors() cef, aqo_query_texts aqt
567+
FROM public.show_cardinality_errors(true) cef, aqo_query_texts aqt
569568
WHERE aqt.query_hash = cef.id;
570-
num | error | query_text
571-
-----+-----------+-------------------------------------------------------------------------------------------
572-
1 | 9.69e+02 | SELECT str FROM expln(' +
573-
| | EXPLAIN (ANALYZE, COSTS OFF, SUMMARY OFF, TIMING OFF) +
574-
| | SELECT count(*) FROM +
575-
| | (SELECT * FROM t WHERE x % 3 < (SELECT avg(x) FROM t t0 WHERE t0.x = t.x)) AS q1 +
576-
| | JOIN +
577-
| | (SELECT * FROM t WHERE x % 3 < (SELECT avg(x) FROM t t0 WHERE t0.x <> t.x)) AS q2+
578-
| | ON q1.x = q2.x+1; +
579-
| | ') AS str WHERE str NOT LIKE '%Memory Usage%';
580-
2 | 3.27e+02 | SELECT +
581-
| | num, +
582-
| | to_char(error, '9.99EEEE')::text AS error +
583-
| | FROM public.show_cardinality_errors() +
584-
| | WHERE error > 0.;
585-
3 | 0.00e+00 | CREATE TABLE t AS SELECT (gs.* / 50) AS x FROM generate_series(1,1000) AS gs;
586-
4 | 0.00e+00 | SELECT public.clean_aqo_data();
587-
5 | 0.00e+00 | CREATE TABLE t1 AS SELECT mod(gs,10) AS x, mod(gs+1,10) AS y +
588-
| | FROM generate_series(1,1000) AS gs;
589-
(5 rows)
569+
num | error | query_text
570+
-----+-------+------------
571+
(0 rows)
590572

591573
DROP EXTENSION aqo;

‎preprocessing.c‎

Lines changed: 12 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -407,12 +407,19 @@ disable_aqo_for_query(void)
407407

408408
/*
409409
* Examine a fully-parsed query, and return TRUE iff any relation underlying
410-
* the query is a system relation.
410+
* the query is a system relation or no one relation touched by the query.
411411
*/
412412
static bool
413413
isQueryUsingSystemRelation(Query *query)
414414
{
415-
return isQueryUsingSystemRelation_walker((Node *) query, NULL);
415+
bool trivQuery = true;
416+
bool result;
417+
418+
result = isQueryUsingSystemRelation_walker((Node *) query, &trivQuery);
419+
420+
if (result || trivQuery)
421+
return true;
422+
return false;
416423
}
417424

418425

@@ -451,10 +458,13 @@ isQueryUsingSystemRelation_walker(Node *node, void *context)
451458
Relation rel = table_open(rte->relid, AccessShareLock);
452459
bool is_catalog = IsCatalogRelation(rel);
453460
bool is_aqo_rel = IsAQORelation(rel);
461+
bool *trivQuery = (bool *) context;
454462

455463
table_close(rel, AccessShareLock);
456464
if (is_catalog || is_aqo_rel)
457465
return true;
466+
467+
*trivQuery = false;
458468
}
459469
else if (rte->rtekind == RTE_FUNCTION)
460470
{

‎sql/top_queries.sql‎

Lines changed: 19 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -3,13 +3,15 @@ SET aqo.mode = 'disabled';
33
SET aqo.force_collect_stat = 'on';
44

55
--
6-
-- num of generate_series(1,1000000) query should be the first
6+
-- Dummy test. CREATE TABLE shouldn't find in the ML storage. But a simple
7+
-- select must be in. Also here we test on gathering a stat on temp and plain
8+
-- relations.
79
--
8-
SELECT count(*) FROM generate_series(1,1000000);
9-
SELECT num FROM top_time_queries(10) AS tt WHERE
10-
tt.fspace_hash = (SELECT fspace_hash FROM aqo_queries WHERE
11-
aqo_queries.query_hash = (SELECT aqo_query_texts.query_hash FROM aqo_query_texts
12-
WHERE query_text = 'SELECT count(*) FROM generate_series(1,1000000);'));
10+
CREATE TEMP TABLE ttt AS SELECT count(*) AS cnt FROM generate_series(1,10);
11+
CREATE TABLE ttp AS SELECT count(*) AS cnt FROM generate_series(1,10);
12+
SELECT count(*) AS cnt FROM ttt WHERE cnt % 100 = 0;
13+
SELECT count(*) AS cnt FROM ttp WHERE cnt % 100 = 0;
14+
SELECT num FROM top_time_queries(3);
1315

1416
--
1517
-- num of query uses table t2 should be bigger than num of query uses table t1 and be the first
@@ -21,7 +23,14 @@ CREATE TABLE t2 AS SELECT mod(gs,10) AS x, mod(gs+1,10) AS y
2123
SELECT count(*) FROM (SELECT x, y FROM t1 GROUP BY GROUPING SETS ((x,y), (x), (y), ())) AS q1;
2224
SELECT count(*) FROM (SELECT x, y FROM t2 GROUP BY GROUPING SETS ((x,y), (x), (y), ())) AS q1;
2325

24-
SELECT num FROM top_error_queries(10) AS te WHERE
25-
te.fspace_hash = (SELECT fspace_hash FROM aqo_queries WHERE
26-
aqo_queries.query_hash = (SELECT aqo_query_texts.query_hash FROM aqo_query_texts
27-
WHERE query_text = 'SELECT count(*) FROM (SELECT x, y FROM t2 GROUP BY GROUPING SETS ((x,y), (x), (y), ())) AS q1;'));
26+
SELECT num, to_char(error, '9.99EEEE') FROM show_cardinality_errors(false) AS te
27+
WHERE te.fshash = (
28+
SELECT fspace_hash FROM aqo_queries
29+
WHERE aqo_queries.query_hash = (
30+
SELECT aqo_query_texts.query_hash FROM aqo_query_texts
31+
WHERE query_text = 'SELECT count(*) FROM (SELECT x, y FROM t2 GROUP BY GROUPING SETS ((x,y), (x), (y), ())) AS q1;'
32+
)
33+
);
34+
35+
-- Should return zero
36+
SELECT count(*) FROM show_cardinality_errors(true);

‎sql/unsupported.sql‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -159,7 +159,7 @@ EXPLAIN (COSTS OFF)
159159
SELECT
160160
num,
161161
to_char(error, '9.99EEEE')::text AS error
162-
FROM public.show_cardinality_errors()
162+
FROM public.show_cardinality_errors(true)
163163
WHERE error > 0.;
164164

165165
DROP TABLE t,t1 CASCADE;
@@ -168,7 +168,7 @@ SELECT public.clean_aqo_data();
168168

169169
-- TODO: figure out with remaining queries in the ML storage.
170170
SELECT num, to_char(error, '9.99EEEE')::text AS error, query_text
171-
FROM public.show_cardinality_errors() cef, aqo_query_texts aqt
171+
FROM public.show_cardinality_errors(true) cef, aqo_query_texts aqt
172172
WHERE aqt.query_hash = cef.id;
173173

174174
DROP EXTENSION aqo;

‎t/001_pgbench.pl‎

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -134,24 +134,24 @@
134134
'analytical queries in pgbench (disabled mode)');
135135

136136
$res = $node->safe_psql('postgres',
137-
"SELECT count(*) FROM top_error_queries(10) v
138-
JOIN aqo_query_texts t ON (t.query_hash = v.fspace_hash)
137+
"SELECT count(*) FROM show_cardinality_errors(false) v
138+
JOIN aqo_query_texts t ON (t.query_hash = v.id)
139139
WHERE v.error > 0. AND t.query_text LIKE '%pgbench_accounts%'");
140140
is($res, 3);
141141
$res = $node->safe_psql('postgres',
142-
"SELECT * FROM top_error_queries(10) v
143-
JOIN aqo_query_texts t ON (t.query_hash = v.fspace_hash)
142+
"SELECT * FROM show_cardinality_errors(false) v
143+
JOIN aqo_query_texts t ON (t.query_hash = v.id)
144144
WHERE v.error > 0. AND t.query_text LIKE '%pgbench_accounts%'");
145145
note("\n TopN: \n $res \n");
146146
$res = $node->safe_psql('postgres',
147-
"SELECT v.error, t.query_text FROM top_error_queries(10) v
148-
JOIN aqo_query_texts t ON (t.query_hash = v.fspace_hash)
147+
"SELECT v.error, t.query_text FROM show_cardinality_errors(false) v
148+
JOIN aqo_query_texts t ON (t.query_hash = v.id)
149149
WHERE v.error > 0.");
150150
note("\n Queries: \n $res \n");
151151
$res = $node->safe_psql('postgres',
152152
"SELECT count(*) FROM top_time_queries(10) v
153153
WHERE v.execution_time > 0.");
154-
is($res, 5);
154+
is($res, 3);
155155

156156
# ##############################################################################
157157
#

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