On Thu, Feb 8, 2024 at 4:41 PM Stephen Frost <sfrost@xxxxxxxxxxx> wrote:
Greetings,
* Ron Johnson (ronljohnsonjr@xxxxxxxxx) wrote:
> On Thu, Feb 8, 2024 at 12:48 PM Magnus Hagander <magnus@xxxxxxxxxxxx> wrote:
> > On Thu, Feb 8, 2024, 17:05 Ron Johnson <ronljohnsonjr@xxxxxxxxx> wrote:
> >> (PG 14, if it matters.)
> >>
> >> What's the purpose of fetch mode, as opposed to streaming mode? Is it a
> >> legacy of bygone days that just hasn't been deprecated, or is there
> >> something I don't understand from reading
> >> https://www.postgresql.org/docs/14/app-pgbasebackup.html?
> >
> > Your backup can go to a single file with it, which it can't do in
> > streaming. Which means it can also be sent through a pipe.
>
> But isn't the whole purpose of pg_basebackup (running it on Node B, when
> the database instance is Node A)?
Something seems missing from this question?
The word "streaming".
Should be "But isn't streaming the whole purpose of pg_basebackup"?
Being able to send through a pipe might allow someone to send directly
to a tape device or to a Bacula system or similar.
Yeah, ok.
I use PgBackRest, though, and can't imagine single-threading any reasonably-sized database. In fact, one of the tasks on my mental TODO list is to research how to use PgBackRest to initialize a replica instance prior to starting Streaming Replication.
> > It also needs one connection instead of two to the server, if that's
> > limited.
>
> It's 2024, not 2011. Who can't spare an extra connection?
Changing max_wal_senders requires a database-wide restart, so..
To not have some wiggle room is poor planning
Not sure where you're going with this though. Are you arguing that
fetch mode should be removed?
No. Just curious about its use cases.
If so, why? If that's not the angle,
then what is? Would you suggest some better documentation of the
option? I'm sure a proposal to improve the docs would be welcome, if
there's something confusing about them and this option.
A hint as to the use-case for the non-default "streaming" option would be enlightening.
