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Re: WITH RECURSIVE doesn't work properly for me - Mailing list pgsql-general

From Jing Fan
Subject Re: WITH RECURSIVE doesn't work properly for me
Date
Msg-id CA+BectnCMjSOY3KdUB4Wv18+ukDHrub4=B94yazbSUFBXTzWDA@mail.gmail.com
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In response to Re: WITH RECURSIVE doesn't work properly for me  (Albe Laurenz <laurenz.albe@wien.gv.at>)
Responses Re: WITH RECURSIVE doesn't work properly for me
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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

for we have min(dist),
so it should be like

src_id | dest_id | dist
--------+---------+------
   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:
> Why the one inside does not do anything? It won't be executed?

It is 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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