Hi, Am Dienstag, den 19.03.2019, 11:22 -0400 schrieb Robert Haas: > It's torn pages that I am concerned about - the server is writing and > we are reading, and we get a mix of old and new content. We have been > quite diligent about protecting ourselves from such risks elsewhere, > and checksum verification should not be held to any lesser standard.
If we see a checksum failure on an otherwise correctly read block in online mode, we retry the block on the theory that we might have read a torn page. If the checksum verification still fails, we compare its LSN to the LSN of the current checkpoint and don't mind if its newer. This way, a torn page should not cause a false positive either way I think?. If it is a genuine storage failure we will see it in the next pg_checksums run as its LSN will be older than the checkpoint. The basebackup checksum verification works in the same way. I am happy to look into further option about how to make things better, but I am not sure what the actual problem might be that you mention above. I will see whether I can stress-test the patch a bit more but I've already taxed the SSD on my company notebook quite a bit during the development of this so will see whether I can get some real server hardware somewhere. Michael -- Michael Banck Projektleiter / Senior Berater Tel.: +49 2166 9901-171 Fax: +49 2166 9901-100 Email: michael.ba...@credativ.de credativ GmbH, HRB Mönchengladbach 12080 USt-ID-Nummer: DE204566209 Trompeterallee 108, 41189 Mönchengladbach Geschäftsführung: Dr. Michael Meskes, Jörg Folz, Sascha Heuer Unser Umgang mit personenbezogenen Daten unterliegt folgenden Bestimmungen: https://www.credativ.de/datenschutz
