Robert Haas <robertmh...@gmail.com> writes: > The point I was trying to make is that if you retroactively change the > cost of a path after you've already done add_path(), it's too late to > change your mind about whether to keep the path. At least according > to my current understanding, that's the root of this problem in the > first place. On top of that, add_path() and other routines that deal > with RelOptInfo path lists expect surviving paths to be ordered by > descending cost; if you frob the cost, they might not be properly > ordered any more.
Hadn't been paying attention to this thread, but I happened to notice Robert's comment here, and I strongly agree: it is *not* cool to be changing a path's cost (or, really, anything else about it) after it's already been given to add_path. add_path has already made irreversible choices on the basis of what it was given. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers