Distinct LISTAGG that is inside a subquery in the SELECT list - sql

Question

Here is a minimal working example of what I'm trying to do and what I'm getting:
I have a query as follows:
/*
with tran_party as -- ALL DUMMY DATA ARE IN THESE CTE FOR YOUR REFERENCE
(select 1 tran_party_id, 11 transaction_id, 101 team_id_redirect
from dual
union all
select 2, 11, 101 from dual
union all
select 3, 11, 102 from dual
union all
select 4, 12, 103 from dual
union all
select 5, 12, 103 from dual
union all
select 6, 12, 104 from dual
union all
select 7, 13, 104 from dual
union all
select 8, 13, 105 from dual),
tran as
(select 11 transaction_id, 1001 account_id, 1034.93 amount from dual
union all
select 12, 1001, 2321.89 from dual
union all
select 13, 1002, 3201.47 from dual),
account as
(select 1001 account_id, 111 team_id from dual
union all
select 1002, 112 from dual),
team as
(select 101 team_id, 'UUU' as team_code from dual
union all
select 102, 'VV' from dual
union all
select 103, 'WWW' from dual
union all
select 104, 'XXXXX' from dual
union all
select 105, 'Z' from dual)
-- */
-- The Actual Query
select a.account_id,
t.transaction_id,
(select listagg (tm_redir.team_code, ', ')
within group (order by tm_redir.team_code)
from tran_party tp_redir
inner join team tm_redir
on tp_redir.team_id_redirect = tm_redir.team_id
inner join tran t_redir
on tp_redir.transaction_id = t_redir.transaction_id
where t_redir.account_id = a.account_id
and t_redir.transaction_id != t.transaction_id)
as teams_redirected
from tran t inner join account a on t.account_id = a.account_id;
NOTE: tran_party.team_id_redirect is a foreign key that references team.team_id.
Current output:
ACCOUNT_ID TRANSACTION_ID TEAMS_REDIRECTED
---------- -------------- ----------------
1001 11 WWW, WWW, XXXXX
1001 12 UUU, UUU, VV
1002 13
Expected output:
I want the repeated items in TEAMS_REDIRECTED column to be selected only once, like this:
ACCOUNT_ID TRANSACTION_ID TEAMS_REDIRECTED
---------- -------------- ----------------
1001 11 WWW, XXXXX
1001 12 UUU, VV
1002 13
What I tried:
Instead of selecting from tran_party directly, I wrote an inline view that selects distinct values from tran_party like this:
select a.account_id,
t.transaction_id,
(select listagg (tm_redir.team_code, ', ')
within group (order by tm_redir.team_code)
from (select distinct transaction_id, team_id_redirect -- Note this inline view
from tran_party) tp_redir
inner join team tm_redir
on tp_redir.team_id_redirect = tm_redir.team_id
inner join tran t_redir
on tp_redir.transaction_id = t_redir.transaction_id
where t_redir.account_id = a.account_id
and t_redir.transaction_id != t.transaction_id)
as teams_redirected
from tran t inner join account a on t.account_id = a.account_id;
While this does give me the expected output, when I use this solution in my actual code, it takes about 13 seconds to retrieve just one row. Thus I cannot use what I already tried.
Any help will be appreciated.

Answer 1

The following method gets rid of the in-line view to fetch duplicates, it uses REGEXP_REPLACE and RTRIM on the LISTAGG function to get the distinct result set in the aggregated list. Thus, it won't do more than one scan.
Adding this piece to your code,
RTRIM(REGEXP_REPLACE(listagg (tm_redir.team_code, ',')
WITHIN GROUP (ORDER BY tm_redir.team_code),
'([^,]+)(,\1)+', '\1'),
',')
Modified query-
SQL> with tran_party as -- ALL DUMMY DATA ARE IN THESE CTE FOR YOUR REFERENCE
2 (select 1 tran_party_id, 11 transaction_id, 101 team_id_redirect
3 from dual
4 union all
5 select 2, 11, 101 from dual
6 union all
7 select 3, 11, 102 from dual
8 union all
9 select 4, 12, 103 from dual
10 union all
11 select 5, 12, 103 from dual
12 union all
13 select 6, 12, 104 from dual
14 union all
15 select 7, 13, 104 from dual
16 union all
17 select 8, 13, 105 from dual),
18 tran as
19 (select 11 transaction_id, 1001 account_id, 1034.93 amount from dual
20 union all
21 select 12, 1001, 2321.89 from dual
22 union all
23 select 13, 1002, 3201.47 from dual),
24 account as
25 (select 1001 account_id, 111 team_id from dual
26 union all
27 select 1002, 112 from dual),
28 team as
29 (select 101 team_id, 'UUU' as team_code from dual
30 union all
31 select 102, 'VV' from dual
32 union all
33 select 103, 'WWW' from dual
34 union all
35 select 104, 'XXXXX' from dual
36 union all
37 select 105, 'Z' from dual)
38 -- The Actual Query
39 select a.account_id,
40 t.transaction_id,
41 (SELECT RTRIM(
42 REGEXP_REPLACE(listagg (tm_redir.team_code, ',')
43 WITHIN GROUP (ORDER BY tm_redir.team_code),
44 '([^,]+)(,\1)+', '\1'),
45 ',')
46 from tran_party tp_redir
47 inner join team tm_redir
48 on tp_redir.team_id_redirect = tm_redir.team_id
49 inner join tran t_redir
50 on tp_redir.transaction_id = t_redir.transaction_id
51 where t_redir.account_id = a.account_id
52 and t_redir.transaction_id != t.transaction_id)
53 AS teams_redirected
54 from tran t inner join account a on t.account_id = a.account_id
55 /
ACCOUNT_ID TRANSACTION_ID TEAMS_REDIRECTED
---------- -------------- --------------------
1001 11 WWW,XXXXX
1001 12 UUU,VV
1002 13
SQL>