Oracle Cloud DB 19c bug with JSON_ARRAYAGG - oracle

Question

I try to use JSON_ARRAYAGG into select and get bug result with the same data
SELECT json_object(
'buy' VALUE JSON_ARRAYAGG(b.buysum),
'total' VALUE JSON_ARRAYAGG(b.totalsum)
)
FROM (
select *
from view_count_sum
ORDER BY date_rw DESC
FETCH FIRST 10 ROWS ONLY
) b
ORDER BY b.date_rw;
As a result i get JSON with 2 arrays which have decrease data order in first array and wrong order in second array
{"buy":[4168,4145,4130,4101,4068,4042,4008,3940,3900,3858],"total":[7778,7258,7333,7442,7546,7607,7642,7683,7718,7745]}
If I replace position JSON_ARRAYAGG in select I see right order for first array again and wrong order for second array
SELECT json_object(
'total' VALUE JSON_ARRAYAGG(b.totalsum),
'buy' VALUE JSON_ARRAYAGG(b.buysum)
)
FROM (
select *
from view_count_sum
ORDER BY date_rw DESC
FETCH FIRST 10 ROWS ONLY
) b
ORDER BY b.date_rw;
See result:
{"total":[7778,7745,7718,7683,7642,7607,7546,7442,7333,7258],"buy":[4168,3858,3900,3940,4008,4042,4068,4101,4130,4145]}
The order second and any other arrays is wrong. The first element is right but all other are reversed

Answer 1

Starting with some data where the expected order is easy to see:
CREATE TABLE view_count_sum (date_rw, buysum, totalsum) AS
SELECT 10, 1, 1 FROM DUAL UNION ALL
SELECT 9, 2, 2 FROM DUAL UNION ALL
SELECT 8, 3, 3 FROM DUAL UNION ALL
SELECT 7, 4, 4 FROM DUAL UNION ALL
SELECT 6, 5, 5 FROM DUAL UNION ALL
SELECT 5, 6, 6 FROM DUAL UNION ALL
SELECT 4, 7, 7 FROM DUAL UNION ALL
SELECT 3, 8, 8 FROM DUAL UNION ALL
SELECT 2, 9, 9 FROM DUAL UNION ALL
SELECT 1, 10, 10 FROM DUAL;
Then, if you do:
SELECT json_object(
'buy' VALUE JSON_ARRAYAGG(b.buysum),
'total' VALUE JSON_ARRAYAGG(b.totalsum)
) AS json
FROM (
select *
from view_count_sum
ORDER BY date_rw DESC
FETCH FIRST 10 ROWS ONLY
) b
ORDER BY b.date_rw;
Then the output is:
JSON
{"buy":[1,2,3,4,5,6,7,8,9,10],"total":[1,10,9,8,7,6,5,4,3,2]}
Instead, if you add the ORDER BY clause into the aggregation functions:
SELECT json_object(
'buy' VALUE JSON_ARRAYAGG(b.buysum ORDER BY b.date_RW DESC),
'total' VALUE JSON_ARRAYAGG(b.totalsum ORDER BY b.date_RW DESC)
) AS json
FROM (
select *
from view_count_sum
ORDER BY date_rw DESC
FETCH FIRST 10 ROWS ONLY
) b;
Then the output is:
JSON
{"buy":[1,2,3,4,5,6,7,8,9,10],"total":[1,2,3,4,5,6,7,8,9,10]}
db<>fiddle for Oracle 18