A customer's upgrade failed, and it took me a while to
figure out that the problem was that they had set
"vacuum_defer_cleanup_age=10000" on the new cluster.
The consequence was that the "vacuumdb --freeze" that
takes place before copying commit log files failed to
freeze "pg_database".
That caused later updates to the table to fail with
"Could not open file "pg_xact/0000": No such file or directory."
I think it would increase the robustness of pg_upgrade to
force "vacuum_defer_cleanup_age" to 0 on the new cluster.
Suggested patch attached.
Yours,
Laurenz Albe
