We attempted to pg_upgrade a database on a replication slave, and got the error:
error while creating link for relation "<schema>.<tablename>" ("/var/lib/postgresql-ext/PG_9.2_201204301/19171/141610397" to "/var/lib/postgresql-ext/PG_9.5_201510051/16401/9911696"): No such file or directory
The missing table turned out to be an unlogged table, and the data file for it was not present on the slave machine. That's reasonable. In our case we are able to start over from a snapshot and drop all the unlogged tables before trying again.
However, this problem was not caught by the `--check` command. I'm looking at the source code and it appears that pg_upgrade does not attempt to verify relation filenodes actually exist before proceeding, whether using --check or not.
Should it? I assume the reasoning is because it would take a long time and perhaps the benefit of doing so would be minimal?
