Re: Range Types and extensions

On Mon, Jun 6, 2011 at 6:23 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Merlin Moncure <mmoncure@gmail.com> writes:
>> I vote for at minimum the type itself and ANYRANGE to be in core.
>> From there you could make it like arrays where the range type is
>> automatically generated for each POD type.  I would consider that for
>> sure on basis of simplicity in user-land unless all the extra types
>> and operators are a performance hit.
>
> Auto-generation of range types isn't going to happen, simply because the
> range type needs more information than is provided by the base type
> declaration.  (First, you need a btree opclass, and second, you need a
> "next" function if it's a discrete type.)
>
> By my count there are only about 20 datatypes in core for which it looks
> sensible to provide a range type (ie, it's a non-deprecated,
> non-composite type with a standard default btree opclass).  For that
> many, we might as well just build 'em in.

right. hm -- can you have multiple range type definitions for a
particular type?  I was thinking about a type reduction for casting
like we have for arrays: select '[1,3)'::int{}. but maybe that isn't
specific enough?

merlin