Re: Logical replication on two identical databases but diff versions

>> Is this expected ?

Yes, this is expected.

>> If this is expected, that means i can have a
>> no downtime upgrade ?

Indeed you can.

>> Is this correct?

This is correct.

On Fri, Jun 17, 2022 at 2:35 PM Vijaykumar Jain <
vijaykumarjain(dot)github(at)gmail(dot)com> wrote:

> Hi,
>
> i have two db servers pg12 and pg14 and they have exactly the same data in
> all schemas and tables. I tried linking both by setting wal_level=logical
> and make pg12 publisher and pg14 subscriber (with copy_data = false,
> create_slot = false, enabled = false)
> Then i created a logical replication slot on pg12 and enabled subscription
> and logical replication was running just fine and all changes from pg12
> going to pg14...
> Is this expected ? I did not play with any of advancing of lsn anywhere...
>
> If this is expected, that means i can have a pg12 cluster of primary and
> replica ... then i can take the replica out of cluster , make it writable
> using pg_promote and then pg_upgrade it to pg14 and then link it like above
> to old pg12 via logical replication...and then slowly after ensuring no
> issues, phase out pg12 and replace it with pg14, no downtime upgrade ?
>
> Is this correct? (Of course no schema changes while this is being done)
> and i set max_wal_size to a large value to retain enough wals.
>
>
>