Hi, Thank you for your answer. Here is the requested information. select last_value from seq_name; The difference was less than 32 except one sequence with difference equal to 32 The cache used for sequence creation was 1. Thank you once again! Dănuț Soare > On 15 May 2024, at 14:01, Laurenz Albe <laurenz.albe@xxxxxxxxxxx> wrote: > > On Wed, 2024-05-15 at 11:03 +0300, Danut Soare wrote: >> I’m upgrading the PostgreSQL version from 12 to 16 using pg_upgrade utility >> with -k option. After upgrading the database, before starting any application >> processing, on checking the last value of some sequences, the value has been >> changed to a value different from the original value. Not all but some of the >> sequences have modified value. I’ve repeated the upgrade several times and >> each time the same sequences have changed with the same values. I’ve expected >> that the upgrade would not interfere with the application data … >> This is the upgrade command: >> >> /usr/pgsql-16/bin/pg_upgrade \ >> —old-datadir=/u01/pgrdb/12/app \ >> —new-data for=/u01/pgrdb/16/app \ >> —old-bindir=/usr/pgsql-12/bin \ >> —new-bindir=/usr/pgsql-16/bin \ >> -k > > How exactly did you determine the current sequence value before and after > the upgrade? Was the difference less than 32? If yes, that is normal, > because sequences don't WAL log every single nextval() call. > Also, what CACHE setting did you use in CREATE SEQUENCE? That will have an > influence, and the difference could be bigger. > > If the sequence moved backward, that would be a bug. If it moves forward, > that is to be expected and OK. > > Yours, > Laurenz Albe
