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Re: About connectby() again

From: Joe Conway <mail(at)joeconway(dot)com>
To: Masaru Sugawara <rk73(at)sea(dot)plala(dot)or(dot)jp>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: About connectby() again
Date: 2002-09-26 23:32:08
Message-ID: 3D9398F8.1070202@joeconway.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Masaru Sugawara wrote:
> The previous patch fixed an infinite recursion bug in 
> contrib/tablefunc/tablefunc.c:connectby. But, other unmanageable error
> seems to occur even if a table has commonplace tree data(see below).
> 
> I would think the patch, ancestor check, should be
> 
>   if (strstr(branch_delim || branchstr->data || branch_delim,
>                        branch_delim || current_key || branch_delim))
> 
> This is my image, not a real code. However, if branchstr->data includes
> branch_delim, my image will not be perfect.

Good point. Thank you Masaru for the suggested fix.

Attached is a patch to fix the bug found by Masaru. His example now produces:

regression=# SELECT * FROM connectby('connectby_tree', 'keyid', 
'parent_keyid', '11', 0, '-') AS t(keyid int, parent_keyid int, level int, 
branch text);
  keyid | parent_keyid | level |  branch
-------+--------------+-------+----------
     11 |              |     0 | 11
     10 |           11 |     1 | 11-10
    111 |           11 |     1 | 11-111
      1 |          111 |     2 | 11-111-1
(4 rows)

While making the patch I also realized that the "no show branch" form of the 
function was not going to work very well for recursion detection. Therefore 
there is now a default branch delimiter ('~') that is used internally, for 
that case, to enable recursion detection to work. If you need a different 
delimiter for your specific data, you will have to use the "show branch" form 
of the function.

If there are no objections, please apply. Thanks,

Joe

Attachment: contrib-tablefunc-fixes-2.1.patch
Description: text/plain (4.8 KB)

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