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* Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object
@ 2024-01-03 16:15 Oscar van Baten <info@oxcro.com>
0 siblings, 1 reply; 5+ messages in thread
From: Oscar van Baten @ 2024-01-03 16:15 UTC (permalink / raw)
To: pgsql-bugs@lists.postgresql.org
/*
Hi,
We've upgraded one of our instances from 14.10 to 16.1 at AWS
All fine, except for a certain output which became different.
At another instance running at 14.7 we are able to reproduce this correct
answer.
Removing the `DISTINCT` or replacing `(SELECT a.id)` with `a.id` does solve
it.
It looks like a reference issue.
You can reproduce with the query below.
PS: I did scan https://wiki.postgresql.org/wiki/Todo but was not able to
find a similar issue.
It does look like this one:
https://www.postgresql.org/message-id/3536307.1703952795%40sss.pgh.pa.us
But not sure if it's the same issue
*/
DROP TABLE IF EXISTS pg_temp.alldata;
create temp table pg_temp.alldata AS
(
SELECT 'val_A' AS id
);
SELECT
a.id as table_value,
STRING_AGG( 'val_B', ', ') AS string_agg_value,
JSON_AGG
(
JSON_BUILD_OBJECT
(
'val_1', a.id,
'val_2', (SELECT a.id)
)
) AS zzz_2
FROM pg_temp.alldata a
GROUP BY id;
at:
PostgreSQL 14.7 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 7.3.1
20180712 (Red Hat 7.3.1-12), 64-bit
output:
table_value|string_agg_value|zzz_2 |
-----------+----------------+----------------------------------------+
val_A |val_B |[{"val_1" : "val_A", "val_2" : "val_A"}]|
at:
PostgreSQL 16.1 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 7.3.1
20180712 (Red Hat 7.3.1-12), 64-bit
output:
table_value|string_agg_value|zzz_2 |
-----------+----------------+----------------------------------------+
val_A |val_B |[{"val_1" : "val_A", "val_2" : "val_B"}]| --
why is val_B suddenly here?
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object
@ 2024-01-03 16:56 Tom Lane <tgl@sss.pgh.pa.us>
parent: Oscar van Baten <info@oxcro.com>
0 siblings, 1 reply; 5+ messages in thread
From: Tom Lane @ 2024-01-03 16:56 UTC (permalink / raw)
To: Oscar van Baten <info@oxcro.com>; +Cc: pgsql-bugs@lists.postgresql.org
Oscar van Baten <info@oxcro.com> writes:
> We've upgraded one of our instances from 14.10 to 16.1 at AWS
> All fine, except for a certain output which became different.
> At another instance running at 14.7 we are able to reproduce this correct
> answer.
> Removing the `DISTINCT` or replacing `(SELECT a.id)` with `a.id` does solve
> it.
> It looks like a reference issue.
> You can reproduce with the query below.
Hi, I failed to reproduce this. I get the expected output
table_value | string_agg_value | zzz_2
-------------+------------------+------------------------------------------
val_A | val_B | [{"val_1" : "val_A", "val_2" : "val_A"}]
(1 row)
both in HEAD and at 16.1 release (3edc6580c). It seems to me that
either you have some relevant non-default planner setting, or this
is an AWS-specific bug. Could we see the output of
EXPLAIN (VERBOSE, SETTINGS)
for this query on the troublesome system?
We do have an open report of a problem with DISTINCT aggregates,
https://www.postgresql.org/message-id/flat/18264-e363593d7e9feb7d%40postgresql.org
but it's unclear whether this is the same.
regards, tom lane
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object
@ 2024-01-03 18:01 Oscar van Baten <info@oxcro.com>
parent: Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 2 replies; 5+ messages in thread
From: Oscar van Baten @ 2024-01-03 18:01 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-bugs@lists.postgresql.org
Hi Tom,
There you go:
v14.7
QUERY PLAN
|
----------------------------------------------------------------------------------------------------------------------------------------+
GroupAggregate (cost=94.38..128.98 rows=200 width=96)
|
Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
(json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text|
Group Key: a.id
|
-> Sort (cost=94.38..97.78 rows=1360 width=32)
|
Output: a.id
|
Sort Key: a.id
|
-> Seq Scan on pg_temp_684.alldata a (cost=0.00..23.60 rows=1360
width=32) |
Output: a.id
|
SubPlan 1
|
-> Result (cost=0.00..0.01 rows=1 width=32)
|
Output: a.id
|
Settings: effective_cache_size = '8014960kB', jit = 'off', search_path =
'public, public, "$user"' |
Query Identifier: -1271634773772018342
|
v16.1
QUERY PLAN
|
----------------------------------------------------------------------------------------------------------------------------------------+
GroupAggregate (cost=94.38..128.98 rows=200 width=96)
|
Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
(json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text|
Group Key: a.id
|
-> Sort (cost=94.38..97.78 rows=1360 width=32)
|
Output: a.id
|
Sort Key: a.id
|
-> Seq Scan on pg_temp.alldata a (cost=0.00..23.60 rows=1360
width=32) |
Output: a.id
|
SubPlan 1
|
-> Result (cost=0.00..0.01 rows=1 width=32)
|
Output: a.id
|
Settings: effective_cache_size = '16179496kB', jit = 'off', temp_buffers =
'64MB', search_path = 'public, public, "$user"' |
Query Identifier: 1935934247983289476
|
Will try to compare the planner settings too.
Regards,
Oscar
Op wo 3 jan 2024 om 17:56 schreef Tom Lane <tgl@sss.pgh.pa.us>:
> Oscar van Baten <info@oxcro.com> writes:
> > We've upgraded one of our instances from 14.10 to 16.1 at AWS
> > All fine, except for a certain output which became different.
> > At another instance running at 14.7 we are able to reproduce this correct
> > answer.
> > Removing the `DISTINCT` or replacing `(SELECT a.id)` with `a.id` does
> solve
> > it.
> > It looks like a reference issue.
>
> > You can reproduce with the query below.
>
> Hi, I failed to reproduce this. I get the expected output
>
> table_value | string_agg_value | zzz_2
> -------------+------------------+------------------------------------------
> val_A | val_B | [{"val_1" : "val_A", "val_2" : "val_A"}]
> (1 row)
>
> both in HEAD and at 16.1 release (3edc6580c). It seems to me that
> either you have some relevant non-default planner setting, or this
> is an AWS-specific bug. Could we see the output of
> EXPLAIN (VERBOSE, SETTINGS)
> for this query on the troublesome system?
>
> We do have an open report of a problem with DISTINCT aggregates,
>
> https://www.postgresql.org/message-id/flat/18264-e363593d7e9feb7d%40postgresql.org
> but it's unclear whether this is the same.
>
> regards, tom lane
>
>
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object
@ 2024-01-03 18:19 Oscar van Baten <info@oxcro.com>
parent: Oscar van Baten <info@oxcro.com>
1 sibling, 0 replies; 5+ messages in thread
From: Oscar van Baten @ 2024-01-03 18:19 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; pgsql-bugs@lists.postgresql.org
I've found that v16.1 has 2 new settings:
enable_presorted_aggregate
recursive_worktable_factor
When I SET enable_presorted_aggregate = OFF: (non default)
The result changes to the correct one.
QUERY PLAN
GroupAggregate (cost=94.38..128.98 rows=200 width=96)
Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
(json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text
Group Key: a.id
-> Sort (cost=94.38..97.78 rows=1360 width=32)
Output: a.id
Sort Key: a.id
-> Seq Scan on pg_temp.alldata a (cost=0.00..23.60 rows=1360
width=32)
Output: a.id
SubPlan 1
-> Result (cost=0.00..0.01 rows=1 width=32)
Output: a.id
Settings: effective_cache_size = '16179496kB', enable_presorted_aggregate =
'off', jit = 'off', temp_buffers = '64MB', search_path = 'public, public,
"$user"'
Query Identifier: 1935934247983289476
And SET jit = ON; kept the wrong result.
Regards,
Oscar
Op wo 3 jan 2024 om 19:01 schreef Oscar van Baten <info@oxcro.com>:
> Hi Tom,
>
> There you go:
>
> v14.7
> QUERY PLAN
> |
>
> ----------------------------------------------------------------------------------------------------------------------------------------+
> GroupAggregate (cost=94.38..128.98 rows=200 width=96)
> |
> Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
> (json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text|
> Group Key: a.id
> |
> -> Sort (cost=94.38..97.78 rows=1360 width=32)
> |
> Output: a.id
> |
> Sort Key: a.id
> |
> -> Seq Scan on pg_temp_684.alldata a (cost=0.00..23.60 rows=1360
> width=32) |
> Output: a.id
> |
> SubPlan 1
> |
> -> Result (cost=0.00..0.01 rows=1 width=32)
> |
> Output: a.id
> |
> Settings: effective_cache_size = '8014960kB', jit = 'off', search_path =
> 'public, public, "$user"' |
> Query Identifier: -1271634773772018342
> |
>
>
>
> v16.1
> QUERY PLAN
> |
>
> ----------------------------------------------------------------------------------------------------------------------------------------+
> GroupAggregate (cost=94.38..128.98 rows=200 width=96)
> |
> Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
> (json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text|
> Group Key: a.id
> |
> -> Sort (cost=94.38..97.78 rows=1360 width=32)
> |
> Output: a.id
> |
> Sort Key: a.id
> |
> -> Seq Scan on pg_temp.alldata a (cost=0.00..23.60 rows=1360
> width=32) |
> Output: a.id
> |
> SubPlan 1
> |
> -> Result (cost=0.00..0.01 rows=1 width=32)
> |
> Output: a.id
> |
> Settings: effective_cache_size = '16179496kB', jit = 'off', temp_buffers =
> '64MB', search_path = 'public, public, "$user"' |
> Query Identifier: 1935934247983289476
> |
>
> Will try to compare the planner settings too.
>
> Regards,
> Oscar
>
> Op wo 3 jan 2024 om 17:56 schreef Tom Lane <tgl@sss.pgh.pa.us>:
>
>> Oscar van Baten <info@oxcro.com> writes:
>> > We've upgraded one of our instances from 14.10 to 16.1 at AWS
>> > All fine, except for a certain output which became different.
>> > At another instance running at 14.7 we are able to reproduce this
>> correct
>> > answer.
>> > Removing the `DISTINCT` or replacing `(SELECT a.id)` with `a.id` does
>> solve
>> > it.
>> > It looks like a reference issue.
>>
>> > You can reproduce with the query below.
>>
>> Hi, I failed to reproduce this. I get the expected output
>>
>> table_value | string_agg_value | zzz_2
>>
>>
>> -------------+------------------+------------------------------------------
>> val_A | val_B | [{"val_1" : "val_A", "val_2" : "val_A"}]
>> (1 row)
>>
>> both in HEAD and at 16.1 release (3edc6580c). It seems to me that
>> either you have some relevant non-default planner setting, or this
>> is an AWS-specific bug. Could we see the output of
>> EXPLAIN (VERBOSE, SETTINGS)
>> for this query on the troublesome system?
>>
>> We do have an open report of a problem with DISTINCT aggregates,
>>
>> https://www.postgresql.org/message-id/flat/18264-e363593d7e9feb7d%40postgresql.org
>> but it's unclear whether this is the same.
>>
>> regards, tom lane
>>
>>
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object
@ 2024-01-03 18:20 Tom Lane <tgl@sss.pgh.pa.us>
parent: Oscar van Baten <info@oxcro.com>
1 sibling, 0 replies; 5+ messages in thread
From: Tom Lane @ 2024-01-03 18:20 UTC (permalink / raw)
To: Oscar van Baten <info@oxcro.com>; +Cc: pgsql-bugs@lists.postgresql.org, David Rowley <dgrowleyml@gmail.com>
Oscar van Baten <info@oxcro.com> writes:
> There you go:
> GroupAggregate (cost=94.38..128.98 rows=200 width=96)
> Output: a.id, string_agg(DISTINCT 'val_B'::text, ', '::text),
> (json_agg(json_build_object('val_1', a.id, 'val_2', (SubPlan 1))))::text|
Ah, that gave me the clue I needed (maybe I should have deduced it
from your Subject, but I plead ENOCAFFEINE). Your query as submitted
doesn't use DISTINCT in the STRING_AGG call, but that's needed to
trigger the bug. And it is indeed the same bug as #18264: it begins
at the same commit, and David's WIP patch fixes it.
regards, tom lane
^ permalink raw reply [nested|flat] 5+ messages in thread
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2024-01-03 16:15 Bugreport: incorrect result in 16.1 in query with string_agg(distinct+json_build_object Oscar van Baten <info@oxcro.com>
2024-01-03 16:56 ` Tom Lane <tgl@sss.pgh.pa.us>
2024-01-03 18:01 ` Oscar van Baten <info@oxcro.com>
2024-01-03 18:19 ` Oscar van Baten <info@oxcro.com>
2024-01-03 18:20 ` Tom Lane <tgl@sss.pgh.pa.us>
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