Re: Primary Key Increment Doesn't Seem Correct Under Table Partition

Thanks and Regards
Yan Cheng CHEOK


--- On Tue, 1/26/10, Alban Hertroys <dalroi@solfertje.student.utwente.nl> wrote:

> From: Alban Hertroys <dalroi@solfertje.student.utwente.nl>
> Subject: Re: [GENERAL] Primary Key Increment Doesn't Seem Correct Under Table Partition
> To: "Yan Cheng Cheok" <yccheok@yahoo.com>
> Cc: pgsql-general@postgresql.org
> Date: Tuesday, January 26, 2010, 6:36 PM
> On 26 Jan 2010, at 11:00, Yan Cheng
> Cheok wrote:
>
> > However, whenever I insert row into measurement table,
> I realize its primary key value is going from 2, 4, 6, 8,
> 10...
> >
> > May I know how can I prevent this?
>
> Apparently nextval on that sequence gets called multiple
> times in your queries.
>

Do you have any idea why it happens so?

> > Also, is it necessary to create index for
> measurement_id found in measurement's child table? I am
> concern on the read speed.
>
>
> Serials don't create indexes, only a sequence. Primary keys
> create indexes (to guarantee uniqueness) - foreign keys do
> not.
> So yes, you want an index on that column in the child
> table.
>

But...

measurement table does contains

CONSTRAINT pk_measurement_id PRIMARY KEY (measurement_id),

when measurement_0 child table inherits from measurement table, isn't it will inherit PRIMARY KEY (measurement_id)?

Do I still have to create index for measurement_0.measurement_id ?

> Alban Hertroys
>
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