On Thu, Dec 31, 2020 at 02:27:44PM -0500, Stephen Frost wrote: > Greetings, > > * Bruce Momjian (br...@momjian.us) wrote: > > On Wed, Dec 30, 2020 at 12:52:46PM -0800, Andres Freund wrote: > > > A question from a colleague made me wonder if there are scenarios where > > > two subsequent crashes could lead to wrong WAL to be applied. > > > > > > Imagine the following scenario > > > [ xlog page 1 ][ xlog page 2 ][ xlog page 3 ][ xlog page 4 ] > > > ^flush ^write ^insert > > > > > > if the machine crashes in this moment, we could end up with a situation > > > where page 1, 3, 4 made it out out to disk, but page 2 wasn't. > > > > I don't see any flaw in your logic. Seems we have to zero out all > > future WAL files, not just to the end of the current one, or at least > > clear xlp_pageaddr on each future page. > > I've wondered before if we should be doing a timeline switch at the end > of crash recovery...
For a while we had trouble tracking timeline switches, but I think we might be fine on that now. -- Bruce Momjian <br...@momjian.us> https://momjian.us EnterpriseDB https://enterprisedb.com The usefulness of a cup is in its emptiness, Bruce Lee
