On Mon, 15 Feb 2021 18:55:14 +0100 Paolo Saudin <paolosaudin@xxxxxxxxx> wrote: > Hi all, > I have two servers, a primary and a secondary one with a streaming replica > setup. > Today I noticed that some sequences are not lined-up, the replica ones are > well ahead, while the records number is the same. How is it possible? This is because sequences are not WAL logged on every nextval() call, but by batch of sequence cache+32 values. As standbys are fed with WAL stream from primary, their sequences appears jump, then stall, then jump, etc. See: https://git.postgresql.org/cgit/postgresql.git/tree/src/backend/commands/sequence.c?id=f672df5fdd22dac14c98d0a0bf5bbaa6ab17f8a5#n52 https://git.postgresql.org/cgit/postgresql.git/tree/src/backend/commands/sequence.c?id=f672df5fdd22dac14c98d0a0bf5bbaa6ab17f8a5#n661 I'm not sure if this is documented somewhere... ?
