On Tue, 4 Jan 2011 11:07:00 -0800 (PST), Dennis Gearon
<gearond@xxxxxxxxxxxxx> wrote:
I haven't been able to find anywhere, easily, in the documentation
using google
where a list of allowed data types for primary keys is.
So, UUIDs can be primary keys?
Any issues wtih them on sorting or paging of index tables, etc.?
Disadvantage
* aren't ordered in way as records are added to DB.
* 128bit length (PSQL stores them as 128bit value)
* slower to generate you need to use random number generator
* ... if you do select * on table with two uuids you will need to
scroll GUI to see data :)
* ... really unhandy if you want to make manual updates :)
Advantage:
* simple to generate, and 128bit random is almost globally unique,
* you have your id, before executing query, (in contrast to all this
autoincrement) so you may put it in dependant rows
* almost every platform has UUID generator
Advantage / disadvantage
* depending on UUID generator, UUID can store some "privacy"
information e.g. MAC address of your card, such UUID.
Personally I prefer pooled incremental id's. Fast, unique, you have Id
before query - but you need to write "code" by self.
Also, the documentation says that UUIDs are 128 bit value, but never
explicitly
says that's how it's stored. Nor does it use one of the nice, blue
headered
tables for UUID (or ENUM) showing storage and other attributes as it
does for
numeric, character,boolean, date/time, binary, monetary, geometric,
or network
types.
Dennis Gearon
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