Alvaro Herrera wrote:
> Heikki Linnakangas wrote:
> > If you add a new datatype, and define b-tree operators for it, what
> > is required to create a minmax opclass for it? Would it be possible
> > to generalize the functions in brin_minmax.c so that they can be
> > reused for any datatype (with b-tree operators) without writing any
> > new C code? I think we're almost there; the only thing that differs
> > between each data type is the opcinfo function. Let's pass the type
> > OID as argument to the opcinfo function. You could then have just a
> > single minmax_opcinfo function, instead of the macro to generate a
> > separate function for each built-in datatype.
>
> Yeah, that's how I had that initially. I changed it to what it's now as
> part of a plan to enable building cross-type opclasses, so you could
> have "WHERE int8col=42" without requiring a cast of the constant to type
> int8. This might have been a thinko, because AFAICS it's possible to
> build them with a constant opcinfo as well (I changed several other
> things to support this, as described in a previous email.) I will look
> into this later.
I found out that we don't really throw errors in such cases anymore; we
insert casts instead. Maybe there's a performance argument that it
might be better to use existing cross-type operators than casting, but
justifying this work just turned a lot harder. Here's a patch that
reverts opcinfo into a generic function that receives the type OID.
I will look into adding some testing mechanism for the union support
proc; with that I will just consider the patch ready for commit and will
push.
--
Álvaro Herrera http://www.2ndQuadrant.com/
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