The CONNECT BY patch from evgen potemkin has been ported to pg 8.2... and it's now in BSD License...
I will test it on our test environement Le jeudi 25 janvier 2007 à 11:08 +0000, Gregory Stark a écrit : > Hm, having skimmed through the Evgen Potemkin's recursive queries patch I find > it quite different from what I was expecting. My own thinking was headed off > in a different direction. > > Basically the existing patch reimplements a new kind of join which implements > a kind of nested loop join (with newer versions adding a kind of hash join) > which feeds a new kind of tuplestore called a tupleconn. > > I was thinking to have a new node above a standard join. The new node would > repeatedly feed back down to the join the results of the previous iteration > and reexecute the join to get the next generation. > > I think my approach is more in line with the DB2/ANSI "WITH" style query which > is expected to do a breadth-first search. The Oracle CONNECT BY syntax is > expected to do a depth first search. > > I have two major issues with the repeated-join model though. > > a) Ideally we would want to switch between nested loop, merge join, and hash > join depending on the size of the previous generation. That means the join > node wouldn't be the same type of join for all the iterations. This is > important since in most applications you're traversing either up or down a > tree and are likely starting with very few nodes but often ending up with very > broad levels with many nodes. No single type of join will be appropriate for > the whole plan execution. > > b) I do want to be able to support depth-first searching too. I'm not sure how > to reconcile that with the repeated-join conceptual model. We could always > resort the entire result set after generating it but that seems like an > unsatisfactory solution. > _______________________________________________ Ce message et les �ventuels documents joints peuvent contenir des informations confidentielles. Au cas o� il ne vous serait pas destin�, nous vous remercions de bien vouloir le supprimer et en aviser imm�diatement l'exp�diteur. Toute utilisation de ce message non conforme � sa destination, toute diffusion ou publication, totale ou partielle et quel qu'en soit le moyen est formellement interdite. Les communications sur internet n'�tant pas s�curis�es, l'int�grit� de ce message n'est pas assur�e et la soci�t� �mettrice ne peut �tre tenue pour responsable de son contenu.
