BUG #17457: pg_rewind fatal failure when $PGDATA/log is a soft-link
The following bug has been logged on the website:
Bug reference: 17457
Logged by: Christopher Bruhy
Email address: cbruhy@gmail.com
PostgreSQL version: 14.2
Operating system: CentOS 8.4.2105
Description:
We run a 2 server setup with one (1) Primary streaming updates to one (1)
Replica.
On both, the log files on a separate volume with a soft-link from the
original $PGDATA/log to this new location.
$ ln -s /some/other/location/log $PGDATA/log
The path itself to the log is the same on both servers, but is not the same
physical volume.
postgresql.conf is modified with:
log_directory = '/some/other/location/log'
Simulating a failover event, the Primary is stopped and the Replica is
promoted, no problem.
Then simulating damage to the Primary's WAL directory, we deleted all WAL
files.
On recovery of the original Primary to become a new Replica, we run:
$ ./bin/pg_rewind --target-pgdata $PGDATA --source-server
'application_name=standby_1 host=<primaryHostName> port=<primaryPgPort>
user=<replicatorUser> dbname=postgres sslmode=prefer' --progress
pg_rewind fails with exit code 1 reporting
INFO pg_rewind: connected to server
INFO pg_rewind: servers diverged at WAL location BBD/FF0000A0 on
timeline 3
INFO pg_rewind: rewinding from last common checkpoint at BBD/FF000028
on timeline 3
INFO pg_rewind: reading source file list
INFO pg_rewind: reading target file list
INFO pg_rewind: reading WAL in target
INFO pg_rewind: fatal: file "log" is of different type in source and
target
Unfortunately, this foils our attempt to automate failover using
pg_rewind.
Can pg_rewind ignore the fact that this is a soft-link and push forward?
Also applies to PostgreSQL 12 & 13.
System Info:
Linux version 4.18.0-305.3.1.el8.x86_64 (mockbuild@kbuilder.bsys.centos.org)
(gcc version 8.4.1 20200928 (Red Hat 8.4.1-1) (GCC))
Intel Xeon-Gold 5120
54 GB RAM
postgresql14-server-14.2-1PGDG.rhel8.x86_64
postgresql14-contrib-14.2-1PGDG.rhel8.x86_64
postgresql14-libs-14.2-1PGDG.rhel8.x86_64
postgresql14-14.2-1PGDG.rhel8.x86_64
postgresql14-devel-14.2-1PGDG.rhel8.x86_64