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.
Patch to do this attached, for discussion. -- Simon Riggs http://www.EnterpriseDB.com/
one_freeze_then_max_freeze.v5.patch
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