Re: pgsql: Add deduplication to nbtree.

Peter Geoghegan <pg(at)bowt(dot)ie> writes:
> Attached patch shows how this could work. I prefer my original
> approach, but I can see the argument for doing it this way.

This does seem a bit duplicative ... and shouldn't both code paths
include a final "Assert(d == vacposting->ndeletedtids)"? So maybe
we're better off just rejecting the Coverity complaint.

> If we keep my original approach, we should still add a new
> "ItemPointerIsValid(&itup->t_tid)" assertion that covers the plain
> tupe case in a way that mirrors the current "_bt_posting_valid(itup)"
> assert.

Another thing that maybe bears closer scrutiny is the size calculation.
It seems a bit confused as to whether the offset of the posting list
within the tuple, or the total tuple size, or both, needs to be
MAXALIGN'd.

regards, tom lane