On 19 Apr 2010, at 20:26, cojack wrote: >> Alban Hertroys wrote: >> >> It would help if you'd show us what result you expect from ordering the >> above. >> >> Most people would order this by path I think. However that doesn't match >> your sort column and I can't think of any method that would give results >> in such an arbitrary order as you seem to be specifying - unless you set >> it by hand like you do.
> Yes, you have right, for example I create new idea of stored data in table: > > here is a paste: http://pastebin.com/4pX5cM7j -- never expired link > > As you can see, I have noodes with numeric type, those nodes present a sort > position by self. And If I type ORDER BY path; I will have data like I want > to have: http://pastebin.com/R4z01LC5 -- never expired link > > Again, you can see now grouped data in his nodes, this is the outputed data > I wanted. If you know better way to make this WITHOUT recursive queries, > give me a hint. Aha, looks like you want to sort each tree level by some user-specified order. You should realise that ltree was contributed before Postgres supported (recursive) CTE's. If you're using ltree in combination with recursive CTE's you're doing twice the work that you need to do - ltree was created as a means to make recursive queries possible in the first place. I think you have basically two ways to go about this: 1). The way you're doing this in your new examples should work, although I'd probably make the ordering numbers part of the category names and split those off when I read them. For example: 27 | 1|Top 28 | 1|Top.1|Science 29 | 1|Top.2|Hobby 30 | 1|Top.3|Colors 31 | 1|Top.1|Science.1|Physics 32 | 1|Top.1|Science.2|Chemistry 33 | 1|Top.1|Science.3|Biology 34 | 1|Top.1|Science.4|History 35 | 1|Top.2|Hobby.1|Fishing 36 | 1|Top.2|Hobby.2|Football 37 | 1|Top.3|Colors.1|Black 38 | 1|Top.3|Colors.2|Red 39 | 1|Top.3|Colors.3|Blue 40 | 1|Top.1|Science.5|Archeology 41 | 1|Top.2|Hobby.3|Swimming 42 | 1|Top.3|Colors.4|Gray 43 | 1|Top.3|Colors.5|Purple 44 | 1|Top.3|Colors.6|Brown 45 | 1|Top.2|Hobby.4|Climbing 2). Drop the ltree column and go with a truly recursive approach, something like this: CREATE TABLE node ( category text NOT NULL PRIMARY KEY, sort_order int NOT NULL, parent text REFERENCES tree (category) ON UPDATE CASCADE ON DELETE CASCADE ); WITH RECURSIVE tree AS ( SELECT * FROM node WHERE parent IS NULL UNION ALL SELECT node.* FROM tree, node WHERE node.parent = tree.category ORDER BY sort_order ) SELECT * FROM tree; I haven't actually used recursive CTE's before so there may be some errors in the above, but you get the general idea. Alban Hertroys -- Screwing up is an excellent way to attach something to the ceiling. !DSPAM:737,4bcd773910411833268189! -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
