Re: Remove pg_am.amindexnulls?

On Fri, Jan 7, 2011 at 8:20 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> David Fetter <david(at)fetter(dot)org> writes:
>> On Fri, Jan 07, 2011 at 08:08:38PM -0500, Tom Lane wrote:
>>> Anyone against simplifying matters by getting rid of
>>> pg_am.amindexnulls?
>
>> I guess the only potential use for it would be for some kind of am
>> that *couldn't* index nulls out of the gate.  Might their be such AMs
>> on the horizon?
>
> Well, there are AMs around already that can't index nulls: hash is one,
> and GIN was one until an hour ago.  The question though is whether
> anything outside the AM needs to know about that behavior.  Between
> amclusterable, amsearchnulls, and amoptionalkey, I believe that we have
> quite enough flags already to cover what anything else actually
> needs-to-know about the AM's behavior.

I've pretty much come to the conclusion that pg_am is much better at
providing the illusion of abstraction than it is at providing actual
abstraction. IIUC, the chances that a third-party AM would need to
patch core are nearly 100% anyway, so I'm not inclined to spend much
mental energy trying to figure out what flags it might hypothetically
need.

In other words, go nuts.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company