On Jul 28, 2009, at 6:15 AM, Peter Eisentraut wrote:
On Monday 27 July 2009 14:50:30 Alvaro Herrera wrote:
We've developed some code to implement fixed-length datatypes for
well
known digest function output (MD5, SHA1 and the various SHA2 types).
These types have minimal overhead and are quite complete, including
btree and hash opclasses.
We're wondering about proposing them for inclusion in pgcrypto. I
asked
Marko Kreen but he is not sure about it; according to him it would be
better to have general fixed-length hex types. (I guess it would be
possible to implement the digest types as domains over those.)
I think equipping bytea with a length restriction would be a very
natural,
simple, and useful addition. If we ever want to move the bytea
type closer to
the SQL standard blob type, this will need to happen anyway.
The case for separate fixed-length data types seems very dubious,
unless you
can show very impressive performance numbers. For one thing, they
would make
the whole type system more complicated, or in the alternative,
would have
little function and operator support.
bytea doesn't cast well to and from text when you're dealing with hex
data; you end up using the same amount of space as a varchar. What
would probably work well is a hex datatype that internally works like
bytea but requires that the input data is hex (I know you can use
encode/decode, but that added step is a pain). A similar argument
could be made for base64 encoded data.
--
Decibel!, aka Jim C. Nasby, Database Architect deci...@decibel.org
Give your computer some brain candy! www.distributed.net Team #1828
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