Re: Streaming replication: PANIC on tertiary when secondary promoted

I had it "latest" as well.
I'll try to reproduce it again tomorrow.

On 16/06/2021 17:20, Vijaykumar Jain wrote:
> What is your recovery_target_timeline set to on replicas ?
>
> I just did a primary -> replica -> cascading replica setup. and then
> promoted replica as new primary.
> cascading replica was working fine, no restarts required.
>
> for me recovery_target_timeline was set to 'latest'
>
> i have pg14beta installed btw.
>
> initdb -D primary
> The files belonging to this database system will be owned by user "postgres".
> This user must also own the server process.
>
> postgres(at)db:~/playground$ pg_ctl -D primary -l logfile start
> waiting for server to start.... done
> server started
> postgres(at)db:~/playground$ psql
> psql (14beta1)
> Type "help" for help.
>
> postgres=# select pg_create_physical_replication_slot('replica');
> pg_create_physical_replication_slot
> -------------------------------------
> (replica,)
> (1 row)
>
> postgres=# create table t(id int primary key);
> CREATE TABLE
> postgres=# insert into t select x from generate_series(1, 100) x; checkpoint;
> INSERT 0 100
> postgres=# \q
>
> -- create a replica
> postgres(at)db:~/playground$ pg_basebackup -D replica -R -X stream -S
> replica -v -d "dbname=postgres port=5432" -U postgres
> pg_basebackup: initiating base backup, waiting for checkpoint to complete
> pg_basebackup: checkpoint completed
> pg_basebackup: write-ahead log start point: 0/2000028 on timeline 1
> pg_basebackup: starting background WAL receiver
> pg_basebackup: write-ahead log end point: 0/2000138
> pg_basebackup: waiting for background process to finish streaming ...
> pg_basebackup: syncing data to disk ...
> pg_basebackup: renaming backup_manifest.tmp to backup_manifest
> pg_basebackup: base backup completed
> postgres(at)db:~/playground$ vim replica/postgresql.conf
>
> --start the replica (port 5433)
> postgres(at)db:~/playground$ pg_ctl -D replica -l replicalog start
> waiting for server to start.... done
> server started
> postgres(at)db:~/playground$ psql -p 5433 -c 'select count(1) from t;'
> count
> -------
> 100
> (1 row)
>
> postgres(at)db:~/playground$ psql -p 5433
> psql (14beta1)
> Type "help" for help.
>
>
> -- create a replica slot for cascading streaming replication
> postgres=# select pg_create_physical_replication_slot('cascading_replica');
> pg_create_physical_replication_slot
> -------------------------------------
> (cascading_replica,)
> (1 row)
>
> postgres=# \q
>
> -- create a cascading replica off replica
>
> postgres(at)db:~/playground$ pg_basebackup -D cascading_replica -R -X
> stream -S cascading_replica -v -d "dbname=postgres port=5433" -U
> postgres
> pg_basebackup: initiating base backup, waiting for checkpoint to complete
> pg_basebackup: checkpoint completed
> pg_basebackup: write-ahead log start point: 0/3000028 on timeline 1
> pg_basebackup: starting background WAL receiver
> pg_basebackup: write-ahead log end point: 0/30000D8
> pg_basebackup: waiting for background process to finish streaming ...
> pg_basebackup: syncing data to disk ...
> pg_basebackup: renaming backup_manifest.tmp to backup_manifest
> pg_basebackup: base backup completed
> postgres(at)db:~/playground$ vim cascading_replica/postgresql.conf
> postgres(at)db:~/playground$ pg_ctl -D cascading_replica -l creplica start
> waiting for server to start.... done
> server started
>
> -- validate receiving data fine.
> postgres(at)db:~/playground$ psql -p 5434 -c 'select count(1) from t;'
> count
> -------
> 100
> (1 row)
>
>
> -- stop primary
> postgres(at)db:~/playground$ pg_ctl -D primary -l logfile stop
> waiting for server to shut down.... done
> server stopped
>
>
> -- promote replica to new primary
> postgres(at)db:~/playground$ psql -p 5433
> psql (14beta1)
> Type "help" for help.
>
> postgres=# select pg_promote();
> pg_promote
> ------------
> t
> (1 row)
>
> postgres=# select pg_is_in_recovery();
> pg_is_in_recovery
> -------------------
> f
> (1 row)
>
> postgres=# \q
>
> --do some dml, validate changes replayed to new replica.
> postgres(at)db:~/playground$ psql -p 5434 -c 'select count(1) from t;'
> count
> -------
> 100
> (1 row)
>
> postgres(at)db:~/playground$ psql -p 5433 -c 'select count(1) from t;'
> count
> -------
> 100
> (1 row)
>
> postgres(at)db:~/playground$ psql -p 5433 -c 'delete from t where id < 50;'
> DELETE 49
> postgres(at)db:~/playground$ psql -p 5433 -c 'select count(1) from t;'
> count
> -------
> 51
> (1 row)
>
> postgres(at)db:~/playground$ psql -p 5434 -c 'select count(1) from t;'
> count
> -------
> 51
> (1 row)
>
>
> in all my cases. recovery_timeline was set to 'latest'.
> i did not rx any panic messages in logs.