Tom Lane <[EMAIL PROTECTED]> writes: > Martijn van Oosterhout <kleptog@svana.org> writes: > > I've been wondering about that. A while ago the change was made from > > outputting a NOTICE with the EXPLAIN output to returning a resultset. > > If you could agree on what columns to return it might not be so hard > > for the EXPLAIN to return full tuples... > > The major stumbling block to that is that a table is inherently > unordered, so you'd have to devise a labeling scheme to allow the > node-tree structure to be represented properly. And without WITH or > CONNECT BY, it'd be a bit of a PITA for an application to decipher the > labeling scheme again ...
Only if we chose to represent the tree structure in a way that required it (like Oracle). There are other ways to represent tree structures. What if we used integer arrays in an ltree-like way: [0] Nested Loop (cost=0.00..1369.49 rows=8230 width=945) [0,0] Join Filter: ("outer".store_location_ids *= "inner".store_location_id) [0,1] -> Index Scan using idx_cache_ads on cache_ads (cost=0.00..3.17 rows=1 width=219) [0,1,0] Index Cond: ((region_id = 12159) AND (ad_id = 132094)) [0,2] -> Seq Scan on store_location (cost=0.00..1160.59 rows=16459 width=726) Even without any special operators this can be ordered easily. And the code needed to find parent nodes and child nodes exists. -- greg ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq