Re: Domains and supporting functions

On Sun, Feb 19, 2006 at 07:57:42PM +0100, Martijn van Oosterhout wrote:
> On Sun, Feb 19, 2006 at 10:34:02AM -0800, elein wrote:
> > Actually I can do and have done this. It is being tested now.
> > I did create an opclass. It creates a UNIQUE index just fine
> > for the type using the lower() functionality. *If* it passes
> > all of my testing I'll publish it tomorrow on general bits.
> > Perhaps folks can help try to break it when I publish (or
> > if you are around today Sunday, you can test in advance--email me
> > directly.)
>
> How is this different from the citext module I suggested?
>

My implementation is in SQL and plperl only. Also, the lower
case comparisons are only one aspect of the datatype.

> > Now my only complaint is that ORDER BY requires the USING op
> > when it should recognize the information in the opclass for
> > btree > and < for the type of the sort column. I can explain
> > why it doesn't recognize the opclass information, but I think
> > it should.
>
> ORDER BY x ASC is a synonym for ORDER BY x USING >. That's the way it
> is currently. To use ORDER BY by itself you need to call your operators
> < and >.
>

This does not work where x is datatype foo with opclass foo_ops.
In this case, it uses the text > instead of the foo >.

> > Type inheritance for base types should work by inheriting all of the
> > parent's definitions and overriding them only as necessary. What I'm
> > trying to do is to demonstrate that we can weasle this functionality
> > using domains.
>
> Well, you can kind of do this by creating an implicit cast from your
> type to text. Then you can use your type anywhere where text can appear
> (like strpos, length, etc).
>

Yes, I'm leveraging most of the text functions.

> Hope this helps,
> --
> Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> > tool for doing 5% of the work and then sitting around waiting for someone
> > else to do the other 95% so you can sue them.