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Re: FSM rewrite committed, loose ends

From: Robert Treat <xzilla(at)users(dot)sourceforge(dot)net>
To: pgsql-hackers(at)postgresql(dot)org
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Dave Page <dpage(at)pgadmin(dot)org>, Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Gurjeet Singh <singh(dot)gurjeet(at)gmail(dot)com>
Subject: Re: FSM rewrite committed, loose ends
Date: 2008-10-02 15:32:16
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
On Thursday 02 October 2008 08:37:59 Tom Lane wrote:
> Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> > Following that philosophy, I think the idea of adding a new optional
> > "fork name" argument to pg_relation_size() is the right thing to do:
> >
> > pg_relation_size('footable') for size of the main data fork
> > pg_relation_size('footable', 'fsm') for FSM size
> +1.  Note that the second form should also accept 'main' or some such
> for orthogonality.
> > There's currently two variants of both pg_relation_size and
> > pg_total_relation_size, one takes an OID and one takes a relation name
> > as argument. Any objections to having just one of each function, taking
> > a 'regclass'? The user-visible behavior wouldn't change, but I thought
> > I'd ask first in case I'm missing something.
> Um, it would only not change for someone typing
> pg_relation_size('literal').  Something like this:
> 	select sum(pg_relation_size(relname)) from pg_class
> would fail for lack of an implicit cast from name to regclass.
> Now the above is pretty stupid --- it would be faster and more
> schema-safe to be passing pg_class.oid --- so maybe we don't care
> about breaking it.

I would be more concerned about people doing:

select pg_relation_size(tablename) from pg_tables; 

since pg_tables is presented as a more user-friendly option to something like 
pg_class this might be something more widely used, plus we don't have the 
easy way out of just telling them to use the oid instead like we do with 

Robert Treat
Build A Brighter LAMP :: Linux Apache {middleware} PostgreSQL

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