Re: index prefetching

On Thu, Feb 8, 2024 at 3:18 AM Melanie Plageman
<melanieplageman@gmail.com> wrote:
> - kill prior tuple
>
> This optimization doesn't work with index prefetching with the current
> design. Kill prior tuple relies on alternating between fetching a
> single index tuple and visiting the heap. After visiting the heap we
> can potentially kill the immediately preceding index tuple. Once we
> fetch multiple index tuples, enqueue their TIDs, and later visit the
> heap, the next index page we visit may not contain all of the index
> tuples deemed killable by our visit to the heap.

Is this maybe just a bookkeeping problem? A Boolean that says "you can
kill the prior tuple" is well-suited if and only if the prior tuple is
well-defined. But perhaps it could be replaced with something more
sophisticated that tells you which tuples are eligible to be killed.

--
Robert Haas
EDB: http://www.enterprisedb.com