On 01/05/2011 07:31 PM, RadosÅaw Smogura wrote:
* you have your id, before executing query, (in contrast to all this
autoincrement) so you may put it in dependant rows
Do you mean that with a UUID, you don't need to talk to the database at
all, you can generate an ID with no interaction with / involvement with
the database at all? Because other than that, there's not much
difference in how you normally work with them.
With a sequence, you might:
CREATE SEQUENCE x_id_seq;
CREATE TABLE x (
id integer PRIMIARY KEY DEFAULT nextval('x_id_seq'),
y integer
);
INSERT INTO x(y) VALUES (1);
With a uuid, you'd:
CREATE TABLE x (
id uuid PRIMARY KEY DEFAULT uuid_generate_v4(),
y integer
);
INSERT INTO x(y) VALUES (1);
In either case, you can explicitly call the generator function for
seq/uuid - nextval(seqname) or uuid_generate_v4() respectively - or you
can omit the PK column in your inserts and let the database generate it.
Personally I prefer pooled incremental id's. Fast, unique, you have Id
before query - but you need to write "code" by self.
Many libraries / ORMs / etc that interact with Pg will happily take care
of this for you. In fact, I had to fight to convince Hibernate that I
*didn't* want it to increment all my counters in steps of 50.
--
Craig Ringer
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