Re: WITH RECURSIVE doesn't work properly for me
| От | Jing Fan |
|---|---|
| Тема | Re: WITH RECURSIVE doesn't work properly for me |
| Дата | |
| Msg-id | CA+BectnCMjSOY3KdUB4Wv18+ukDHrub4=B94yazbSUFBXTzWDA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: WITH RECURSIVE doesn't work properly for me (Albe Laurenz <laurenz.albe@wien.gv.at>) |
| Ответы |
Re: WITH RECURSIVE doesn't work properly for me
|
| Список | pgsql-general |
If the grouping inside CTE is executed, I don't think it would generate result like
src_id | dest_id | dist
--------+---------+------
3384 | 6236 | 1
3384 | 1739 | 2
3384 | 6236 | 3
3384 | 1739 | 4
3384 | 6236 | 5
3384 | 1739 | 6
3384 | 6236 | 7
3384 | 1739 | 8
3384 | 6236 | 9
3384 | 1739 | 10
3384 | 6236 | 11
--------+---------+------
3384 | 6236 | 1
3384 | 1739 | 2
3384 | 6236 | 3
3384 | 1739 | 4
3384 | 6236 | 5
3384 | 1739 | 6
3384 | 6236 | 7
3384 | 1739 | 8
3384 | 6236 | 9
3384 | 1739 | 10
3384 | 6236 | 11
for we have min(dist),
so it should be like
src_id | dest_id | dist
--------+---------+------
3384 | 6236 | 1
3384 | 1739 | 2
--------+---------+------
3384 | 6236 | 1
3384 | 1739 | 2
other values will be eliminated by min(). It actually generate no new tuples and the iteration should stop.
Best,
Jing
On Tue, Nov 5, 2013 at 9:28 AM, Albe Laurenz <laurenz.albe@wien.gv.at> wrote:
Jing Fan wrote:It is executed.
> Why the one inside does not do anything? It won't be executed?
It might filter out the occasional row, but if you look at
the example I gave you, you'll see that it won't do anything
to keep it from recursing.
Yours,
Laurenz Albe
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