RE: [PATCH] Explain what the default output_plugin_libraries do

Dear Jacob,

> Splitting this concern off from the original report:

Actually this thread was not split on the web archive ;-(. But the proposal is good.

> I'd like to
> backpatch something like the attached so that it's more obvious why
> you might (or might not) want to keep those in the list in the first
> place.
>
> WDYT?

Few comments:

1.
Wondering we need to add descriptions in logical-decoding.sgml. One idea is
something like below, are there better ideas?

```
--- a/doc/src/sgml/logicaldecoding.sgml
+++ b/doc/src/sgml/logicaldecoding.sgml
@@ -783,6 +783,8 @@ DETAIL: Synchronization could lead to data loss, because the remote slot needs
<filename>contrib/test_decoding</filename>
</link>
subdirectory of the PostgreSQL source tree.
+ When you use new output plugins, you must also update
+ <xref linkend="guc-output-plugin-libraries"/>.
</para>
```

2.
```
+ <entry>
+ Decodes the WAL stream into a human-readable text representation.
+ <xref linkend="app-pgrecvlogical"/> uses this plugin by default, so
+ removing it from <literal>output_plugin_libraries</literal> will
+ prevent the use of that utility unless a replacement plugin is
+ installed and explicitly selected with
+ <link linkend="app-pgrecvlogical-option-plugin"><literal>--plugin</literal></link>.
+ </entry>
```

The description may not be accurate because the --plugin is referred only at the
creation phase.

Best regards,
Hayato Kuroda
FUJITSU LIMITED