Re: Partitions Table - Mailing list pgsql-admin

From Tom Lane
Subject Re: Partitions Table
Date
Msg-id 3366.1251383819@sss.pgh.pa.us
Whole thread Raw
In response to Partitions Table  (idris khanafi <idris.khanafi@detik.com>)
List pgsql-admin
idris khanafi <idris.khanafi@detik.com> writes:
> i want to create partitions table :

> *create table advertisements_otomotif (CHECK (select * from
> advertisements where category_id in (select id from categories where
> name='Otomotif'))) INHERITS (advertisements)
> *

This is completely confused.  I'm not sure what you are trying to
accomplish, but you've got at least three problems here:

1. Sub-selects used in expressions need to have their own set of
parentheses, ie you'd need something more like CHECK ((select ...))
to get past that syntax error.

2. The sub-select doesn't appear to return boolean, which is what
the CHECK would require.

3. Sub-selects aren't permitted in CHECK constraints, because they
would almost certainly do the wrong thing --- CHECKs are only checked
when a row in the current table is inserted or updated.  So for example
modification or deletion of a row in the other table might make the
check expression no longer true, but the system wouldn't notice.

I think you might be trying to re-invent foreign keys, but without
an explanation of what it is you hope to accomplish, it's hard to
be sure.

            regards, tom lane

pgsql-admin by date:

Previous
From: "Marc Mamin"
Date:
Subject: GRANT SELECT ON DATABASE
Next
From: "freedomyug@gmail.com"
Date:
Subject: [Commercial] Immediate Opening for PostgreSQL DBA at Efficient Frontier, Chennai