Re: PostgreSQL 16 release announcement draft

[Erik Rijkers]

Op 8/26/23 om 04:51 schreef Jonathan S. Katz:

On 8/24/23 11:17 AM, Erik Rijkers wrote:

Op 8/24/23 om 16:32 schreef Jonathan S. Katz:

On 8/23/23 5:07 PM, David Rowley wrote:

On Thu, 24 Aug 2023 at 05:55, Jonathan S. Katz <jk...@postgresql.org> wrote:

Hi,

When v15 docs have:

"27.2.7. Cascading Replication



"
In PostgreSQL 16, users can perform logical decoding from a standby
instance, meaning a standby can publish logical changes to other servers.
"

Is there a difference between the two?

The cascading replication feature allows a standby server to accept replication connections and stream WAL records to other standbys, acting as a relay. This can be used to reduce the number of direct connections to the primary and also to minimize inter-site bandwidth overheads." why then, in the release draft, is that capability mentioned as something that is new for v16?

Yes. Those docs refer to **physical** replication, where a standby can continue to replicate WAL records to other standbys. In v16, standbys can now publish changes over **logical** replication.

Well, I must assume you are right.



 port |  svn   |     slot_name      | slot_type
------+--------+--------------------+-----------
 6526 | 150003 | pub_6527_from_6526 | logical   <--
(1 row)

I must be confused -- I will be thankful for enlightenment.

Erik

But why is the attached program, running 3 cascading v15 servers, showing 'logical' in the middle server's (port 6526) pg_replication_slots.slot_type ? Surely that is not physical but logical replication?

Thanks,

Jonathan

logrep_cascade_15.sh
Description: application/shellscript