On Mon, 21 Oct 2019 at 06:03, Michael Paquier <mich...@paquier.xyz> wrote:
> On Sat, Oct 19, 2019 at 05:03:00AM +0000, tsunakawa.ta...@fujitsu.com > wrote: > > The attached trivial patch fixes the initialization of the fake > > unlogged LSN. Currently, BootstrapXLOG() in initdb sets the initial > > fake unlogged LSN to FirstNormalUnloggedLSN (=1000), but the > > recovery and pg_resetwal sets it to 1. The patch modifies the > > latter two cases to match initdb. > > > > I don't know if this do actual harm, because the description of > > FirstNormalUnloggedLSN doesn't give me any idea. > > From xlogdefs.h added by 9155580: > /* > * First LSN to use for "fake" LSNs. > * > * Values smaller than this can be used for special per-AM purposes. > */ > #define FirstNormalUnloggedLSN ((XLogRecPtr) 1000) > > So it seems to me that you have caught a bug here, and that we had > better back-patch to v12 so as recovery and pg_resetwal don't mess up > with AMs using lower values than that. > I wonder why is that value 1000, rather than an aligned value or a whole WAL page? -- Simon Riggs http://www.2ndQuadrant.com/ <http://www.2ndquadrant.com/> PostgreSQL Solutions for the Enterprise
