Numeric type problems

Hi All,

I hope this is the correct mailing list for this question. But neither
postgresql.org nor google could help me out on this subject.
I did find one disturbing topic on the mailing list archives
(http://archives.postgresql.org/pgsql-admin/2000-05/msg00032.php) but
since it was quite old I'm posting my question anyway.

I'm writing a generic database layer that should support a fixed number
of generic numeric types on a number of databases. At this point it
supports MySQL just fine, but I'm having some trouble finding the right
implementation details for PostgreSQL. Please take a moment to look at
the following table. The field description speaks for itself pretty much
I guess.

Field descr. MySQL PostgreSQL
======================================================================
DB_FIELD_INT8 TINYINT SMALLINT (too big, but best match)
DB_FIELD_INT16 SMALLINT SMALLINT
DB_FIELD_INT32 INT INT
DB_FIELD_INT64 BIGINT BIGINT
DB_FIELD_UINT8 TINYINT UNSIGNED <not supported natively, is it?>
DB_FIELD_UINT16 SMALLINT UNSIGNED <not supported natively, is it?>
DB_FIELD_UINT32 INT UNSIGNED <not supported natively, is it?>
DB_FIELD_UINT64 BIGINT UNSIGNED <not supported natively, is it?>
DB_FIELD_FLOAT FLOAT REAL
DB_FIELD_DOUBLE DOUBLE DOUBLE PRECISION

My problem is obvisouly the unsigned values I really need to be able to
represent properly. I know I can just use the twice as big signed types
and put a constraint on it, but that only works for UINT8, UINT16 and
UINT32 (there is no 128-bit signed integer type, right?): I really need
to have proper 64-bit unsigned integer value support.

I *could* use a BIGINT to represent 64-bit unsigned values, and just
cast the binary data to an unsigned long long (or unsigned __int64 on
win32), but this would leave me with the problem that I couldn't safely
let SQL do comparisons on the value, right?

Is there any solution? I've seen someone suggesting elsewhere that one
should use the OID type, but others said that one shouldn't. I'm pretty
desperate. PostgreSQL would really be my database of choice for our
current project, but I'm afraid we can't use it if I can't get this right...

Thanks in advance for any help!

Bye,
Marc