On Wed, Jan 11, 2023 at 3:28 PM Drouvot, Bertrand <bertranddrouvot...@gmail.com> wrote: > > Hi, > > On 1/11/23 5:17 AM, Bharath Rupireddy wrote: > > On Wed, Jan 11, 2023 at 6:32 AM Michael Paquier <mich...@paquier.xyz> wrote: > >> > >> On Tue, Jan 10, 2023 at 05:25:44PM +0100, Drouvot, Bertrand wrote: > >>> I like the idea of comparing the full page (and not just the LSN) but > >>> I'm not sure that adding the pageinspect dependency is a good thing. > >>> > >>> What about extracting the block directly from the relation file and > >>> comparing it with the one extracted from the WAL? (We'd need to skip the > >>> first 8 bytes to skip the LSN though). > >> > >> Byte-by-byte counting for the page hole? > > I've in mind to use diff on the whole page (minus the LSN). > > >> The page checksum would > >> matter as well, > > Right, but the TAP test is done without checksum and we could also > skip the checksum from the page if we really want to. > > > Right. LSN of FPI from the WAL record and page from the table won't be > > the same, essentially FPI LSN <= table page. > > Right, that's why I proposed to exclude it for the comparison. > > What about something like the attached?
Note that the raw page on the table might differ not just in page LSN but also in other fields, for instance see heap_mask for instance. It masks lsn, checksum, hint bits, unused space etc. before verifying FPI consistency during recovery in verifyBackupPageConsistency(). I think the job of verifying FPI from WAL record with the page LSN is better left to the core - via verifyBackupPageConsistency(). Honestly, pg_waldump is good with what it has currently - LSN checks. +# Extract the binary data without the LSN from the relation's block +sysseek($frel, 8, 0); #bypass the LSN +sysread($frel, $blk, 8184) or die "sysread failed: $!"; +syswrite($blkfrel, $blk) or die "syswrite failed: $!"; I suspect that these tests are portable with the hardcoded values such as above. -- Bharath Rupireddy PostgreSQL Contributors Team RDS Open Source Databases Amazon Web Services: https://aws.amazon.com
