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>
Regards,
[1]
https://www.postgresql.org/message-id/CAMsr+YFjxv0T8Yi1Q=3tvdgviu2bm+fb_-xubtfxhsnldns...@mail.gmail.com
Regards,
--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION
