* Peter Geoghegan (p...@heroku.com) wrote: > On Wed, Jan 25, 2017 at 3:30 PM, Stephen Frost <sfr...@snowman.net> wrote: > > As it is, there are backup solutions which *do* check the checksum when > > backing up PG. This is no longer, thankfully, some hypothetical thing, > > but something which really exists and will hopefully keep users from > > losing data. > > Wouldn't that have issues with torn pages?
No, why would it? The page has either been written out by PG to the OS, in which case the backup s/w will see the new page, or it hasn't been. Our testing has not turned up any issues as yet. That said, it's relatively new and I wouldn't be surprised if we need to do some adjustments in that area, which might be system-dependent even. We could certainly check the WAL for the page that had a checksum error (we currently simply report them, though don't throw away a prior backup if we detect one). This isn't like a case where only half the page made it to the disk because of a system failure though; everything is online and working properly during an online backup. Thanks! Stephen
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