On Wed, 11 May 2022 at 14:38, Justin Pryzby <pry...@telsasoft.com> wrote: > I wonder if this is also relevant. > > 65014000b35 Replace polyphase merge algorithm with a simple balanced k-way > merge.
Thanks for highlighting that. It very much is relevant. In fact, it seems to account for most of the 25% I mentioned. That particular test was sorting 10 million tuples with 4MB of work_mem. I think that "Improve sorting performance (Heikki Linnakangas)" should be moved out from "E.1.3.1.2. Indexes" and put below "E.1.3.1.4. General Performance" The text likely should include the words "disk-based" so that it's clear that it's not the same as the other line about "in-memory sorts". I'd also be open to just having a single line too. I'd vote to put Heikki's name first if we did that. Maybe: * Improve performance of sorting tuples (Heikki Linnakangas, Ronan Dunklau, David Rowley, Thomas Munro) This improves the merging performance of individual on-disk sort batches, reduces memory consumption for in-memory sorts and reduces CPU overheads for certain in-memory sorts. David
