Re: RAC performance and redundancy questions.

Jonathan Lewis wrote:

> Inserts TEND to be directed at a very limited number of blocks
> (and of table if you are not running ASSM, right hand edge of
> index if you have sequence-generated primary keys with a small
> cache on the sequence).
>

<snipped>
>
> It sounds as if you have some serialisation points in your application
> that make it impossible for RAC to scale. Sequences defined as
> NOCACHE, home-grown sequence tables, (freelists 1 freelist groups 1)
> if not running ASSM, right-hand edge problems on indexes that might
> have to be reversed, etc.

To the OP: A couple of thoughts.

If using sequences to generate a surrogate key take a serious look at using a reverse key index for the primary key. For example:

CREATE TABLE t (
id_col NUMBER(10));

ALTER TABLE t
ADD CONSTRAINT pk_t
PRIMARY KEY (id_col)
USING INDEX
PCTFREE 0
REVERSE;

-- 
Daniel A. Morgan
http://www.psoug.org
damorgan_at_x.washington.edu
(replace x with u to respond)