Re: Inaccurate statement about log shipping replication mode

On Mon, 2025-08-25 at 09:58 +0200, Laurenz Albe wrote:
> On Thu, 2025-08-21 at 15:20 +0000, PG Doc comments form wrote:
> > Page: https://www.postgresql.org/docs/17/warm-standby.html
> >
> > The documentation page about Log-Shipping Standby Servers after describing
> > that there are file-based log shipping and record-based log shipping
> > (streaming replication) states: "It should be noted that log shipping is
> > asynchronous, i.e., the WAL records are shipped after transaction commit.".
> > This statement is misleading because the same page includes a section about
> > configuring synchronous streaming replication. To avoid confusion, I think
> > it makes sense to specify that record-based log shipping can be configured
> > as either asynchronous or synchronous.
>
> I think that the statement you quote is not only misleading, but wrong.
> WAL can get shipped before the transaction commits. Perhaps the sentence
> had better be
>
> It should be noted that by default, log shipping is asynchronous, i.e.,
> the primary server does not wait until the standby receives the data.

Here is a patch for that.

Yours,
Laurenz Albe