On Sun, Nov 15, 2020 at 04:37:36PM +0100, Magnus Hagander wrote: > On Tue, Nov 10, 2020 at 5:44 AM Michael Paquier <mich...@paquier.xyz> wrote: >> On Thu, Nov 05, 2020 at 10:57:16AM +0900, Michael Paquier wrote: >>> I was referring to the patch I sent on this thread that fixes the >>> detection of a corruption for the zero-only case and where pd_lsn >>> and/or pg_upper are trashed by a corruption of the page header. Both >>> cases allow a base backup to complete on HEAD, while sending pages >>> that could be corrupted, which is wrong. Once you make the page >>> verification rely only on pd_checksum, as the patch does because the >>> checksum is the only source of truth in the page header, corrupted >>> pages are correctly detected, causing pg_basebackup to complain as it >>> should. However, it has also the risk to cause pg_basebackup to fail >>> *and* to report as broken pages that are in the process of being >>> written, depending on how slow a disk is able to finish a 8kB write. >>> That's a different kind of wrongness, and users have two more reasons >>> to be pissed. Note that if a page is found as torn we have a >>> consistent page header, meaning that on HEAD the PageIsNew() and >>> PageGetLSN() would pass, but the checksum verification would fail as >>> the contents at the end of the page does not match the checksum. >> >> Magnus, as the original committer of 4eb77d5, do you have an opinion >> to share? >> > > I admit that I at some point lost track of the overlapping threads around > this, and just figured there was enough different checksum-involved-people > on those threads to handle it :) Meaning the short answer is "no, I don't > really have one at this point". > > Slightly longer comment is that it does seem reasonable, but I have not > read in on all the different issues discussed over the whole thread, so > take that as a weak-certainty comment.
Which part are you considering as reasonable? The removal-feature part on a stable branch or perhaps something else? -- Michael
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