As always, thanks very much for the confirmation. On Fri, Aug 30, 2024 at 12:18 PM Tom Lane <t...@sss.pgh.pa.us> wrote:
> Morris de Oryx <morrisdeo...@gmail.com> writes: > > From what I've seen in the wild, and can sort out from the source, I > think > > that ltree does *not* need to load rows from heap. > > The comment in ltree_consistent is pretty definitive: > > /* All cases served by this function are exact */ > *recheck = false; > > > I wonder because an ltree GiST index is "lossy" and this behavior is more > > like a lossless strategy. I think that's either because I've > misunderstood > > what "lossy" means in this case, or it's because ltree GiST index *pages > *are > > based on a signature (lossy), while ltree GiST index *leaf entries* > contain > > the full tree/path (lossless.) > > Yeah, the code is not terribly well commented but this bit in ltree.h > appears to be saying that leaf entries contain the original ltree: > > * type of index key for ltree. Tree are combined B-Tree and R-Tree > * Storage: > * Leaf pages > * (len)(flag)(ltree) > * Non-Leaf > * (len)(flag)(sign)(left_ltree)(right_ltree) > * ALLTRUE: (len)(flag)(left_ltree)(right_ltree) > > and that seems consistent with the fact that ltree_consistent > does different things at leaf and non-leaf levels. > > regards, tom lane >
