Thanks for this update. This looks good. Here are a couple of small comments:
1) This sentence is correct English, but I don't recall seeing in the docs such a formulation:
+ Can only be used on slots using a output plugin supporting textual + output.
I'd rather rewrite 'It can only be used' or 'this function can only be used'. I imagine that you could add a reference to logicaldecoding-output-mode as well.
2) s/a output/an output/g
3) The formulation here seems vague as a plugin that generates textual output can call pg_logical_slot_peek_binary_changes as well:
- except that changes are returned as <type>bytea</type>. + except that changes are returned as <type>bytea</type> and that it can + be used on slots using output plugins that only support binary output.
4) What about reformulating the following: + so a <type>text</> can contain it. This is checked in assertion enabled + builds.
"This is checked in builds with assertions enabled."
5) Better to add a newline between two portions sect2.