Martijn van Oosterhout wrote:
On Wed, Jun 28, 2006 at 10:22:45AM +0200, Thomas Hallgren wrote:
Thanks. That would of course work but at the same time it increases the
complexity of my app. Yet another component to install and keep track
of. It's also a bit of an overkill since the only thing I need is an
opaque bit storage. Why is it that PostgreSQL lack a fixed length binary
type similar to the RAW type in Oracle? ISTM that could be very useful
and not very hard to implement.
AIUI, it can't be done because of a basic rule of the type system: the
typmod can't be necessary to interpret the binary representation of a
value. For something like RAW(16) the type would be the oid for "raw"
and the typmod would be 16. However, when reading the value from a disk
page, you're not given the typmod, so you have no way of determining
the length.
OK. I thought you always had a type descriptor handy when reading the binary representation.
I've noticed that the typmod is expected in some receive functions (bpcharrecv and
numeric_recv for instance). Are you saying that there are times when you don't use that?
Regards,
Thomas Hallgren
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