I've gotten really tired of explaining to newbies why stuff involving
char(n) fields doesn't work like they expect. Our current behavior is
not valid per SQL92 anyway, I believe.
I think there is a pretty simple solution now that we have pg_cast:
we could stop treating char(n) as binary-equivalent to varchar/text,
and instead define it as requiring a runtime conversion (which would
be essentially the rtrim() function). The cast in the other direction
would be assignment-only, so that any expression that involves mixed
char(n) and varchar/text operations would be evaluated in varchar
rules after stripping char's insignificant trailing blanks.
If we did this, then operations like WHERE UPPER(charcolumn) = 'FOO'
would work as a newbie expects. I believe that we'd come a lot closer
to spec compliance on the behavior of char(n), too.
Comments?
regards, tom lane
