Re: PG 12 draft release notes

On Tue, May 21, 2019 at 3:49 AM Peter Geoghegan <pg@bowt.ie> wrote:
> On Mon, May 20, 2019 at 3:17 PM Andres Freund <andres@anarazel.de> wrote:
> > <!--
> > Author: Alexander Korotkov <akorotkov@postgresql.org>
> > 2018-07-28 [d2086b08b] Reduce path length for locking leaf B-tree pages during
> > Author: Peter Geoghegan <pg@bowt.ie>
> > 2019-03-25 [f21668f32] Add "split after new tuple" nbtree optimization.
> > -->
> >
> >        <para>
> >         Improve speed of btree index insertions (Peter Geoghegan,
> >         Alexander Korotkov)
> >        </para>
>
> My concern here (which I believe Alexander shares) is that it doesn't
> make sense to group these two items together. They're two totally
> unrelated pieces of work. Alexander's work does more or less help with
> lock contention with writes, whereas the feature that that was merged
> with is about preventing index bloat, which is mostly helpful for
> reads (it helps writes to the extent that writes are also reads).
>
> The release notes go on to say that this item "gives better
> performance for UPDATEs and DELETEs on indexes with many duplicates",
> which is wrong. That is something that should have been listed below,
> under the "duplicate index entries in heap-storage order" item.

+1

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company