We haven't had to create one to update all constituencies. That functionality has worked without issue for us.
One thing we did that might be of interest is the following. There is a “add user-defined constituency” and a “remove user-defined constituency” global change which is built into the system by default I believe. I have used these two to apply and remove constituency codes from constituents based on criteria automatically.
We have a third party service we use for p2p fundraising. When we get gifts of this type, the source field indicates it's p2p. So, we have a query that gets all constituents that have revenue of type p2p that don't have the p2p constituent code, we feed this into the “add user-defined constituency” global change which adds the peer to peer fundraiser constituency.
On the other side, we created a query that gets all constituents with the p2p constituency but no gifts of type p2p, and we feed this selection into the “remove user-defined constituency” global change. The only time this will remove something is if a gift was marked p2p by mistake, but this also works for other things that would expire like memberships, current year donors, you name it.
This is just an example and probably not the best one but using those two global changes in conjunction with one another works very well.
