Re: invalid UTF-8 via pl/perl

I wrote:
>
> I think the attached patch plugs the direct SPI holes as well.

There are two issues with this patch. First, how far if at all should it
be backpatched? All the way, or 8.3, where we tightened the encoding
rules, or not at all?

Second, It produces errors like this:

andrew=# select 'a' || invalid_utf_seq() || 'b';
ERROR: invalid byte sequence for encoding "UTF8": 0xd0
HINT: This error can also happen if the byte sequence does not
match the encoding expected by the server, which is controlled by
"client_encoding".
CONTEXT: PL/Perl function "invalid_utf_seq"
andrew=#

That hint seems rather misleading. I'm not sure what we can do about it
though. If we set the noError param on pg_verifymbstr() we would miss
the error message that actually identified the bad data, so that doesn't
seem like a good plan.

cheers

andrew