Re: Operator class group proposal

On Wed, Dec 13, 2006 at 04:27:09PM -0500, Tom Lane wrote:
> After further thought about the mergejoinable-operators issue and some
> other longstanding planner problems, I have a modest proposal to make:
> we should invent the notion of "operator class groups", which identify
> sets of compatible operator classes.  (I'm not wedded to the name "class
> group"; it seems a bit redundant.  Anyone have a better idea?)  We've
> touched on related ideas in past threads but never really put together
> a concrete proposal.  Here is one.

<snip>

I think it's a good idea, though I would point out that in the examples
given it's the underlying types that are compatable, not the classes.
But I'm unsure if there's a way to use that. These groups seem a
reasonable addition to the existing system.

Other names I can think of:

- type class
- type group
- compatability class
- operator class set

None of which sound any good :(

It's good is that this provides more information about the underlying
types to the system, which improves the possibility of optimisation
(and correctness).

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.