On Wed, Sep 18, 2019 at 10:43 AM Peter Geoghegan <p...@bowt.ie> wrote: > This also suggests that making _bt_dedup_one_page() do raw page adds > and page deletes to the page in shared_buffers (i.e. don't use a temp > buffer page) could pay off. As I went into at the start of this > e-mail, unnecessarily doing expensive things like copying large > posting lists around is a real concern. Even if it isn't truly useful > for _bt_dedup_one_page() to operate in a very incremental fashion, > incrementalism is probably still a good thing to aim for -- it seems > to make deduplication faster in all cases.
I think that I forgot to mention that I am concerned that the kill_prior_tuple/LP_DEAD optimization could be applied less often because _bt_dedup_one_page() operates too aggressively. That is a big part of my general concern. Maybe I'm wrong about this -- who knows? I definitely think that LP_DEAD setting by _bt_check_unique() is generally a lot more important than LP_DEAD setting by the kill_prior_tuple optimization, and the patch won't affect unique indexes. Only very serious benchmarking can give us a clear answer, though. -- Peter Geoghegan
