Re: doc: add note that wal_level=logical doesn't set up logical replication in itself

> On Mar 4, 2026, at 22:11, Euler Taveira <euler(at)eulerto(dot)com> wrote:
>
> On Wed, Mar 4, 2026, at 8:34 AM, Florents Tselai wrote:
>>
>> + <literal>logical</literal> adds information necessary to support
>> + <link linkend="logical-replication">logical replication</link>, which
>> + relies on logical decoding. Each level includes the information logged
>> + at all lower levels.
>>
>
> I'm not opposed to this idea. However, I would like to point out that
>
> 1) "replication" is mentioned for _replica_ which can introduce some confusion
> if we add "logical replication". Maybe it is a good idea to change the sentence
> below from "replication" to "physical replication".
>
>> The default value is replica, which writes enough data to support WAL
>> archiving and replication

I agree with the point. But I think “streaming replication” is more common: “to support WAL archiving and streaming replication”.

>
> 2) There is no link to the sentence above. If you add a link to the logical
> replication section, I would suggest to add a link to the other cases (WAL
> archiving, physical replication) too.
>

I have no objection on updating other docs, but I don’t consider that is a must for the current patch. As Tom mentioned in the other thread, there have been already a lot of inconsistencies, we cannot expect all docs written from a single pen.

> 3) If we are using "logical replication", should we mention "logical decoding"?
> The Logical Replication chapter mentions the use of logical decoding in the
> Architecture section.
>

IMO, we should. Because the option actually enables “logical decoding” that is required by logical replication. So, we mention logical replication in the first place, and to not lose the info, mention “logical decoding” in the second place.

>>
>> Something like:
>> Note that setting this parameter only enables the required WAL format;
>> it does not configure logical replication by itself.
>>
>
> I don't think such note should be added. If the DBA doesn't know how to setup
> logical replication, it should read the Logical Replication chapter.
>

Agreed.

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/