On Thu, 28 Jul 2022 at 15:36, Simon Riggs <simon.ri...@enterprisedb.com> wrote: > > Starting new thread with updated patch to avoid confusion, as > mentioned by David Steele on the original thread: > Original messageid: 20201118020418.GA13408@alvherre.pgsql > On Wed, 18 Nov 2020 at 02:04, Alvaro Herrera <alvhe...@alvh.no-ip.org> wrote: > > On 2020-Nov-17, Simon Riggs wrote: > > > > > As an additional optimization, if we do find a row that needs freezing > > > on a data block, we should simply freeze *all* row versions on the > > > page, not just the ones below the selected cutoff. This is justified > > > since writing the block is the biggest cost and it doesn't make much > > > sense to leave a few rows unfrozen on a block that we are dirtying. > > > > Yeah. We've had earlier proposals to use high and low watermarks: if any > > tuple is past the high watermark, then freeze all tuples that are past > > the low watermark. However this is ancient thinking (prior to > > HEAP_XMIN_FROZEN) and we don't need the low watermark to be different > > from zero, since the original xid is retained anyway. > > > > So +1 for this idea. > > Updated patch attached.
Great idea, yet this patch seems to only freeze those tuples that are located after the first to-be-frozen tuple. It should probably re-visit earlier live tuples to potentially freeze those as well. Kind regards, Matthias van de Meent
