Tom Lane wrote:
SQL92 section 6.1 <data type> quoth
<character string type> ::=
CHARACTER [ <left paren> <length> <right paren> ]
| CHAR [ <left paren> <length> <right paren> ]
...
4) If <length> is omitted, then a <length> of 1 is implicit.
Therefore, writing just "char" is defined as equivalent to "char(1)".
However when length is not defined I think it will generally be safe(r)
to auto-size. In the grand scheme auto-size creates much more sensible
output than a 1-char wide one (even if right-padded to max char-length
of the type).
Also, section 6.10 <cast specification> defines an explicit cast to
a fixed-length string type as truncating or padding to the target
length (LTD):
And PG does this, perfectly. It even right-pads, the other databases
(tried My and Ms) do not...
Possibly you could get what you want by casting to char(10) or so.
Alas the behavior is different. The right padding exists (in PG). So I
cannot get uniform behavior (the other DB's fault I agree for not
supporting cast as varchar).
Unless PG can start throwing an exception in this version when it
truncates to implicit-1, I think it should be forgiving and auto-size..
Is it possible to override this built-in cast function with a create-cast?
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