Re: How does PG Inheritance work?

"Announce" <truthhurts@insightbb.com> writes:
> How does Postgres internally handle inheritance under the following
> scenario?
> Using sample tables similar to a previous post:

>  CREATE TABLE employee(id primary key, name varchar, salary numeric(6,2));
>  CREATE TABLE programmer(language varchar, project varchar) INHERITS
> (employee);
>  CREATE TABLE representative (region varchar) INHERITS (employee);

> Let's say for example's sake, there are 10 million rows of PROGRAMMER data
> but only 100 rows of representative data.  Will a query (select, update,
> insert, etc) on the REPRESENTATIVE table take a performance hit because of
> this?

No.

> It seems like the child-table is really not concrete.

What makes you think that?

In this example, queries against EMPLOYEE take a performance hit due to
the existence of the child tables, because they end up scanning all
three tables.  Queries directly against a child table do not notice the
inheritance relationship at all.

            regards, tom lane