Folks, I'm experimenting with a set of triggers to automagically maintain ltrees-organized tables. I almost have it working, except for a pesky problem with re-ordering groups.
The idea is that I want to set up a set of triggers such that: a) If the user moves item (1) to item (3), then the existing items (2) and (3) will be "bumped down" to (1) and (2), or b) if the user moves item (3) to item (1) then the existing items (1) and (2) will be "bumped up". (btw, the reason I want to use triggers and not data-push functions is that the triggers are *much* more reliable for maintaining the tree fields) I have a set of triggers that are working except for a problem with cycling. What I'm looking for is a reliable, elegant way to make sure that the trigger is executed for each row only once. Currently I'm doing this by only cascade-updating the row adjacent to the one I'm moving. However, this is resulting in a cycle, and I don't see how to break it. Namely: Given: A 1 B 2 C 3 If I move A --> 3 then: B moves to 1 C moves to 2 ... but *so does A* ... and I end up with: A 2 B 1 C 2 So I'm trying to come up with a way to ensure that each row is visited only once, but it doesn't seem to be possible. Ideas? -- --Josh Josh Berkus Aglio Database Solutions San Francisco ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
