Re: Allowing postgresql to accept 0xff syntax for data types that it makes sense for?

Bill Moran <wmoran(at)potentialtech(dot)com> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Other questions you'd have to think about: what is the data type of
>> 0xffffffff; what do you do with 0xffffffffffffffffffffffff (too big
>> even for int8). And it'd likely behoove you to check how Microsoft
>> answers those questions, if you want to point to SQL Server as what's
>> going to keep you out of standards-compatibility problems. (IOW,
>> if 0x ever did get standardized, the text might well match what
>> SQL Server does.)

> MSSQL seems to use it specifically for the equivalent of BYTEA types,
> and it seems to me that should be how it works in PostgreSQL.

Oh really? Wow, I'd just assumed you wanted this as a way to write
integers. That's certainly the use-case I would have personally.
I'm not even sure I like the idea of being able to write byteas without
quotes --- they seem like strings to me, not numbers.

> If an implicit cast from a 4-byte BYTEA to int works now, then it
> should work ... otherwise an explicit cast would be needed, with the
> same behavior if you tried to specify a number that overflows an int
> in any other way.

There's no cast at all from bytea to int. For one thing, it's quite
unclear what endianness should be assumed for such a cast. (To get
unsurprising behavior from what you're describing, I think we'd have
to use a big-endian interpretation of the bytea; but that would be
a pain for a lot of other scenarios, or even for this case if you'd
written a bytea of length other than 4 or 8 bytes.)

regards, tom lane