Mixing
Recursive Iteration in Oracle
1
I have a table like that:
+----+-----+------+
| id | ord | test |
+----+-----+------+
| 1 | 1 | A |
| 1 | 2 | B |
| 1 | 3 | C |
| 2 | 1 | B |
| 2 | 2 | C |
+----+-----+------+
(Here is some code for creating the data)
drop table temp_test;
create table temp_test (id varchar(20), ord varchar(20), test varchar(20));
insert into temp_test (id,ord,test) values ('1','1','A');
insert into temp_test (id,ord,test) values ('1','2','B');
insert into temp_test (id,ord,test) values ('1','3','C');
insert into temp_test (id,ord,test) values ('2','1','B');
insert into temp_test (id,ord,test) values ('2','2','C');
commit;
How could I get the following result?
+----+-----+-------+
| id | ord | test |
+----+-----+-------+
| 1 | 1 | A |
| 1 | 2 | A_B |
| 1 | 3 | A_B_C |
| 2 | 1 | B |
| 2 | 2 | B_C |
+----+-----+-------+
I have tried using LAG(), something like:
select CONCAT(lag(TEST) over (partition by ID order by ord),TEST) AS TEST from temp_test;
but it does not work recursively.
This code works:
SELECT
R1.*,
( SELECT LISTAGG(test, ';') WITHIN GROUP (ORDER BY ord)
FROM temp_test R2
WHERE R1.ord >= R2.ord
AND R1.ID = R2.ID
GROUP BY ID
) AS WTR_KEYWORD_1
FROM temp_test R1
ORDER BY id, ord;
but it is not performant enough for a larger data set.
sql oracle
asked Nov 19 '18 at 16:35
Volokh
1229
add a comment |
1
I have a table like that:
+----+-----+------+
| id | ord | test |
+----+-----+------+
| 1 | 1 | A |
| 1 | 2 | B |
| 1 | 3 | C |
| 2 | 1 | B |
| 2 | 2 | C |
+----+-----+------+
(Here is some code for creating the data)
drop table temp_test;
create table temp_test (id varchar(20), ord varchar(20), test varchar(20));
insert into temp_test (id,ord,test) values ('1','1','A');
insert into temp_test (id,ord,test) values ('1','2','B');
insert into temp_test (id,ord,test) values ('1','3','C');
insert into temp_test (id,ord,test) values ('2','1','B');
insert into temp_test (id,ord,test) values ('2','2','C');
commit;
How could I get the following result?
+----+-----+-------+
| id | ord | test |
+----+-----+-------+
| 1 | 1 | A |
| 1 | 2 | A_B |
| 1 | 3 | A_B_C |
| 2 | 1 | B |
| 2 | 2 | B_C |
+----+-----+-------+
I have tried using LAG(), something like:
select CONCAT(lag(TEST) over (partition by ID order by ord),TEST) AS TEST from temp_test;
but it does not work recursively.
This code works:
SELECT
R1.*,
( SELECT LISTAGG(test, ';') WITHIN GROUP (ORDER BY ord)
FROM temp_test R2
WHERE R1.ord >= R2.ord
AND R1.ID = R2.ID
GROUP BY ID
) AS WTR_KEYWORD_1
FROM temp_test R1
ORDER BY id, ord;
but it is not performant enough for a larger data set.
sql oracle
asked Nov 19 '18 at 16:35
Volokh
1229
add a comment |
1
1
1
1
I have a table like that:
+----+-----+------+
| id | ord | test |
+----+-----+------+
| 1 | 1 | A |
| 1 | 2 | B |
| 1 | 3 | C |
| 2 | 1 | B |
| 2 | 2 | C |
+----+-----+------+
(Here is some code for creating the data)
drop table temp_test;
create table temp_test (id varchar(20), ord varchar(20), test varchar(20));
insert into temp_test (id,ord,test) values ('1','1','A');
insert into temp_test (id,ord,test) values ('1','2','B');
insert into temp_test (id,ord,test) values ('1','3','C');
insert into temp_test (id,ord,test) values ('2','1','B');
insert into temp_test (id,ord,test) values ('2','2','C');
commit;
How could I get the following result?
+----+-----+-------+
| id | ord | test |
+----+-----+-------+
| 1 | 1 | A |
| 1 | 2 | A_B |
| 1 | 3 | A_B_C |
| 2 | 1 | B |
| 2 | 2 | B_C |
+----+-----+-------+
I have tried using LAG(), something like:
select CONCAT(lag(TEST) over (partition by ID order by ord),TEST) AS TEST from temp_test;
but it does not work recursively.
This code works:
SELECT
R1.*,
( SELECT LISTAGG(test, ';') WITHIN GROUP (ORDER BY ord)
FROM temp_test R2
WHERE R1.ord >= R2.ord
AND R1.ID = R2.ID
GROUP BY ID
) AS WTR_KEYWORD_1
FROM temp_test R1
ORDER BY id, ord;
but it is not performant enough for a larger data set.
sql oracle
asked Nov 19 '18 at 16:35
Volokh
1229
I have a table like that:
+----+-----+------+
| id | ord | test |
+----+-----+------+
| 1 | 1 | A |
| 1 | 2 | B |
| 1 | 3 | C |
| 2 | 1 | B |
| 2 | 2 | C |
+----+-----+------+
(Here is some code for creating the data)
drop table temp_test;
create table temp_test (id varchar(20), ord varchar(20), test varchar(20));
insert into temp_test (id,ord,test) values ('1','1','A');
insert into temp_test (id,ord,test) values ('1','2','B');
insert into temp_test (id,ord,test) values ('1','3','C');
insert into temp_test (id,ord,test) values ('2','1','B');
insert into temp_test (id,ord,test) values ('2','2','C');
commit;
How could I get the following result?
+----+-----+-------+
| id | ord | test |
+----+-----+-------+
| 1 | 1 | A |
| 1 | 2 | A_B |
| 1 | 3 | A_B_C |
| 2 | 1 | B |
| 2 | 2 | B_C |
+----+-----+-------+
I have tried using LAG(), something like:
select CONCAT(lag(TEST) over (partition by ID order by ord),TEST) AS TEST from temp_test;
but it does not work recursively.
This code works:
SELECT
R1.*,
( SELECT LISTAGG(test, ';') WITHIN GROUP (ORDER BY ord)
FROM temp_test R2
WHERE R1.ord >= R2.ord
AND R1.ID = R2.ID
GROUP BY ID
) AS WTR_KEYWORD_1
FROM temp_test R1
ORDER BY id, ord;
but it is not performant enough for a larger data set.
sql oracle
sql oracle
asked Nov 19 '18 at 16:35
Volokh
1229
asked Nov 19 '18 at 16:35
Volokh
1229
asked Nov 19 '18 at 16:35
Volokh
1229
asked Nov 19 '18 at 16:35
Volokh
1229
asked Nov 19 '18 at 16:35
Volokh
1229
1229
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
1
Some say the Hierarchical queries are outdated, but they generally perform far better than recursive CTE
SELECT id,
ord,
LTRIM(sys_connect_by_path(test,'_'),'_') as test
FROM temp_test r2 START WITH ord = 1 -- use MIN() to get this if it's not always 1
CONNECT BY PRIOR id = id AND ord = PRIOR ord + 1;
Demo
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
add a comment |
1
you can make use of recursive cte to achieve this
with cte(id,ord,test,concat_val)
as (select id,ord,test,test as concat_val
from temp_test
where ord=1
union all
select a.id,a.ord,a.test,b.concat_val||'_'||a.test
from temp_test a
join cte b
on a.id=b.id
and a.ord=b.ord+1
)
select * from cte order by id,ord
Demo here
https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=78baa20f7f364e653899caf63ce7ada2
answered Nov 19 '18 at 16:59
George Joseph
1,33249
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
Some say the Hierarchical queries are outdated, but they generally perform far better than recursive CTE
SELECT id,
ord,
LTRIM(sys_connect_by_path(test,'_'),'_') as test
FROM temp_test r2 START WITH ord = 1 -- use MIN() to get this if it's not always 1
CONNECT BY PRIOR id = id AND ord = PRIOR ord + 1;
Demo
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
add a comment |
1
Some say the Hierarchical queries are outdated, but they generally perform far better than recursive CTE
SELECT id,
ord,
LTRIM(sys_connect_by_path(test,'_'),'_') as test
FROM temp_test r2 START WITH ord = 1 -- use MIN() to get this if it's not always 1
CONNECT BY PRIOR id = id AND ord = PRIOR ord + 1;
Demo
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
add a comment |
1
1
1
Some say the Hierarchical queries are outdated, but they generally perform far better than recursive CTE
SELECT id,
ord,
LTRIM(sys_connect_by_path(test,'_'),'_') as test
FROM temp_test r2 START WITH ord = 1 -- use MIN() to get this if it's not always 1
CONNECT BY PRIOR id = id AND ord = PRIOR ord + 1;
Demo
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
Some say the Hierarchical queries are outdated, but they generally perform far better than recursive CTE
SELECT id,
ord,
LTRIM(sys_connect_by_path(test,'_'),'_') as test
FROM temp_test r2 START WITH ord = 1 -- use MIN() to get this if it's not always 1
CONNECT BY PRIOR id = id AND ord = PRIOR ord + 1;
Demo
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
answered Nov 19 '18 at 17:31
Kaushik Nayak
18k41230
18k41230
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
add a comment |
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
Thanks, that is the fastest answer.
– Volokh
Nov 19 '18 at 19:15
add a comment |
1
you can make use of recursive cte to achieve this
with cte(id,ord,test,concat_val)
as (select id,ord,test,test as concat_val
from temp_test
where ord=1
union all
select a.id,a.ord,a.test,b.concat_val||'_'||a.test
from temp_test a
join cte b
on a.id=b.id
and a.ord=b.ord+1
)
select * from cte order by id,ord
Demo here
https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=78baa20f7f364e653899caf63ce7ada2
answered Nov 19 '18 at 16:59
George Joseph
1,33249
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
add a comment |
1
you can make use of recursive cte to achieve this
with cte(id,ord,test,concat_val)
as (select id,ord,test,test as concat_val
from temp_test
where ord=1
union all
select a.id,a.ord,a.test,b.concat_val||'_'||a.test
from temp_test a
join cte b
on a.id=b.id
and a.ord=b.ord+1
)
select * from cte order by id,ord
Demo here
https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=78baa20f7f364e653899caf63ce7ada2
answered Nov 19 '18 at 16:59
George Joseph
1,33249
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
add a comment |
1
1
1
you can make use of recursive cte to achieve this
with cte(id,ord,test,concat_val)
as (select id,ord,test,test as concat_val
from temp_test
where ord=1
union all
select a.id,a.ord,a.test,b.concat_val||'_'||a.test
from temp_test a
join cte b
on a.id=b.id
and a.ord=b.ord+1
)
select * from cte order by id,ord
Demo here
https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=78baa20f7f364e653899caf63ce7ada2
answered Nov 19 '18 at 16:59
George Joseph
1,33249
you can make use of recursive cte to achieve this
with cte(id,ord,test,concat_val)
as (select id,ord,test,test as concat_val
from temp_test
where ord=1
union all
select a.id,a.ord,a.test,b.concat_val||'_'||a.test
from temp_test a
join cte b
on a.id=b.id
and a.ord=b.ord+1
)
select * from cte order by id,ord
Demo here
https://dbfiddle.uk/?rdbms=oracle_11.2&fiddle=78baa20f7f364e653899caf63ce7ada2
answered Nov 19 '18 at 16:59
George Joseph
1,33249
answered Nov 19 '18 at 16:59
George Joseph
1,33249
answered Nov 19 '18 at 16:59
George Joseph
1,33249
answered Nov 19 '18 at 16:59
George Joseph
1,33249
1,33249
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
add a comment |
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
That provides the correct result. I will check the performance. Thanks a lot!
– Volokh
Nov 19 '18 at 17:11
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
The result is correct, but the accepted answer is about 100x faster on my data.
– Volokh
Nov 19 '18 at 19:16
add a comment |
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