Re: [HACKERS] Optional message to user when terminating/cancelling backend

> On 12 Aug 2018, at 11:01, Andres Freund <andres@anarazel.de> wrote:
> 
> On August 12, 2018 12:17:59 AM GMT+02:00, Daniel Gustafsson <daniel@yesql.se> wrote:
>>> On 6 Aug 2018, at 09:47, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
>>> 
>>> Has there been any consideration to encodings?
>> 
>> Thats a good point, no =/
>> 
>>> What happens if the message contains non-ASCII characters, and the
>> sending backend is connected to database that uses a different encoding
>> than the backend being signaled?
>> 
>> In the current state of the patch, instead of the message you get:
>> 
>> FATAL: character with byte sequence 0xe3 0x82 0xbd in encoding "UTF8"
>> has
>>          no equivalent in encoding “ISO_8859_5"
>> 
>> Thats clearly not good enough, but I’m not entirely sure what would be
>> the best
>> way forward.  Restrict messages to only be in SQL_ASCII?  Store the
>> encoding of
>> the message and check the encoding of the receiving backend before
>> issuing it
>> for a valid conversion, falling back to no message in case there is
>> none?
>> Neither seems terribly appealing, do you have any better suggestions?
> 
> Restricting to ASCII seems reasonable.

It’s quite restrictive, but it’s the safe option.  I’ve hacked this into the
updated patch, but kept the backend_feedback() function using pg_mbstrlen() at
least for now since it seems the safe option should this be relaxed at some
point.  Also added a small test by copying text from a ja.po file in the tree.

> But note that sqlascii isn't that (it's essentially just arbitrary null terminated data). Easier to relax later.

Yeah, my fingers and brain were not in sync during typing, I meant to say ASCII
there. I blame a lack of coffee.

cheers ./daniel