Re: Logical replication - initial data synchronization

On Fri, Oct 18, 2024 at 7:11 PM Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> wrote:
>
> On Thu, 2024-10-17 at 16:00 -0400, Bruce Momjian wrote:
> > > To me,
> > >
> > > > When logical replication of a table typically starts, a snapshot is
> > > > taken of the table's data on the publisher database and copied to the
> > > > subscriber
> > >
> > > Does not clarify that.
> > >
> > > It's the reason I created this mail: I would like it stated explicitly that the
> > > database process takes care of this for us.
> >
> > Well, you are the first person to report this confusion, and we can't go
> > around explaining what Postgres does and does not do in each section. I
> > would need to hear from other people that this is confusing before
> > making it explicit.
>
> I for one would have interpreted the passive voice here as meaning that the
> database does that automatically. But perhaps active voice can make it even
> clearer:
>
> Ordinarily, when logical replication of a table starts,
> <productname>PostgreSQL</productname> takes a snapshot of the table's
> data on the publisher database and copies these data to the subscriber
>

+1 to say that it is PostgreSQL that does this.

It seems to me the same clarification could be achieved just by adding
1 word ("PostgreSQL") to the original text. e.g.

BEFORE
Logical replication of a table typically starts with taking a snapshot
of the data on the publisher database and copying that to the
subscriber.

AFTER #1 (I added "PostgreSQL")
Logical replication of a table typically starts with PostgreSQL taking
a snapshot of the data on the publisher database and copying that to
the subscriber.

Or, AFTER #2 (I added "PostgreSQL internally")
Logical replication of a table typically starts with PostgreSQL
internally taking a snapshot of the data on the publisher database and
copying that to the subscriber.

======
Kind Regards,
Peter Smith.
Fujitsu Australia