Re: Replaceing records

On Thu, Sep 04, 2003 at 12:17:35PM +0200, Csaba Nagy wrote:
> [philosophical post regarding a missing feature of Postgres]
> 
> I found there's no way to avoid failed inserts because of
> unique constraint violations, causing automatic roll-back of the running
> transaction.
> 
> Now contention on insert has a quite high probability for this operation
> in our application.

Did you ever try this:

insert into test (a, b, c, d) 
  (select 1, 2, 3, 4 where not exists 
    (select 1 from test where a=1 and b=2 and c=3 and d=4)
  );

If your table contains a=1, b=2, c=3, and d=4, nothing will happen, and
there will be no failed transaction.  If your table does not contain a=1,
b=2, c=3, and d=4, you'll get an insert of a row containing 1, 2, 3, 4.