On 2025/05/22 20:53, PG Doc comments form wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/17/logicaldecoding-explanation.html > Description: > > Hi, > I'm referring to this bit at the very end of the page: Creation of a > snapshot is not always possible. In particular, it will fail when connected > to a hot standby. Applications that do not require snapshot export may > suppress it with the NOEXPORT_SNAPSHOT option. > It's not clear what the intention of this is (is it referring only to > physical replication slots?) but as it stands you can export snapshots while > creating a logical replication slot. This should have been possible starting > PG16, I've tested this on PG17.
The description "Creation of a snapshot is not always possible. In particular, it will fail when connected to a hot standby." no longer seems accurate. Since v10 (commit 6c2003f8a1b), exporting snapshots on a standby has been supported.
This description was accurate when the first patch [1] adding that description was written, but I think we just overlooked updating it later.
> As an aside, I think NOEXPORT_SNAPSHOT is from the older syntax of > CREATE_REPLICATION_SLOT and should be swapped with SNAPSHOT 'nothing'.
Yes, so how about the following change?
<para> - Creation of a snapshot is not always possible. In particular, it will - fail when connected to a hot standby. Applications that do not require - snapshot export may suppress it with the <literal>NOEXPORT_SNAPSHOT</literal> + Applications that do not require + snapshot export may suppress it with the <literal>SNAPSHOT 'nothing'</literal> option. </para>
