On Wed, Jul 19, 2006 at 06:23:44PM -0400, Tom Lane wrote: > "Jim C. Nasby" <[EMAIL PROTECTED]> writes: > > On Tue, Jul 11, 2006 at 10:02:49AM -0400, Tom Lane wrote: > >> 1. In a non-rightmost page, we need to include a "high key", or page > >> boundary key, that isn't one of the useful data keys. > > > Why does a leaf page need a boundary key? > > So you can tell whether a proposed insertion ought to go into this page, > or the one to its right. The tree descent logic doesn't guarantee that > you descend to exactly the correct page --- if concurrent page splits > are going on, you might have to "move right" one or more times after > reaching the leaf level. You need the boundary key to make this test > correctly. > > And of course, the reason there's no high key on the rightmost page is > exactly that it has no right-hand neighbor, hence no upper limit on its > delegated key space.
Could you not just scan right and see what the first key was? Thought granted, that means there's a chance of a wasted page scan, but I think that'd be somewhat of a corner case, so it might not be bad. -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org