The background for this patch is that I could easily build urls in plpgsql, but doing the actual encoding of the url parts is painfully slow. The list of available encodings for encode/decode looks quite arbitrary to me, so I can't see any reason this one couldn't be in there.
In modern web scenarios one would probably most likely want to encode the utf8 representation of a text string for inclusion in a url, in which case correct invocation would be ENCODE(CONVERT_TO('some text in database encoding goes here', 'UTF8'), 'uri'), but uri percent-encoding can of course also be used for other text encodings and arbitrary binary data.
This seems like a useful idea to me. I've used the equivalent in Python and it provides more options:
I suggest reviewing that documentation there, because there are a few details that need to be checked carefully. Whether or not space should be encoded as plus and whether certain byte values should be exempt from %-encoding is something that depends on the application. Unfortunately, as far as I can tell there isn't a single version of URL encoding that satisfies all situations (thus explaining the complexity of the Python implementation). It might be feasible to suppress some of the Python options (I'm wondering about the safe= parameter) but I'm pretty sure you at least need the equivalent of quote and quote_plus.
