About connectby() again

On Sat, 07 Sep 2002 10:21:21 -0700
Joe Conway <mail(at)joeconway(dot)com> wrote:

> I just sent in a patch using the ancestor check method. It turned out
> that the performance hit was pretty small on a moderate sized tree.
>
> My test case was a 220000 record bill-of-material table. The tree built
> was 9 levels deep with about 3800 nodes. The performance hit was only
> about 1%.

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.

-- test connectby with int based hierarchy
DROP TABLE connectby_tree;
CREATE TABLE connectby_tree(keyid int, parent_keyid int);

INSERT INTO connectby_tree VALUES(11,NULL);
INSERT INTO connectby_tree VALUES(10,11);
INSERT INTO connectby_tree VALUES(111,11);
INSERT INTO connectby_tree VALUES(1,111);

SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', '11', 0, '-')
AS t(keyid int, parent_keyid int, level int, branch text)

ERROR: infinite recursion detected

Regards,
Masaru Sugawara