Re: range_agg

Thanks Alvaro!

On Mon, Mar 23, 2020 at 4:33 PM Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
>
> Thinking about the on-disk representation, can we do better than putting
> the contained ranges in long-varlena format, including padding; also we
> include the type OID with each element.  Sounds wasteful.  A more
> compact representation might be to allow short varlenas and doing away
> with the alignment padding, put the the type OID just once.  This is
> important because we cannot change it later.

Can you give me some guidance on this? I don't know how to make the
on-disk format different from the in-memory format. (And for the
in-memory format, I think it's important to have actual RangeTypes
inside the multirange.) Is there something in the documentation, or a
README in the repo, or even another type I can follow?

> I'm also wondering if multirange_in() is the right strategy.  Would
it> be sensible to give each range to range_parse or range_parse_bounde, so
> that it determines where each range starts and ends?  Then that function
> doesn't have to worry about each quote and escape, duplicating range
> parsing code.  (This will probably require changing signature of the
> rangetypes.c function, and exporting it; for example have
> range_parse_bound allow bound_str to be NULL and in that case don't mess
> with the StringInfo and just return the end position of the parsed
> bound.)

Yeah, I really wanted to do it that way originally too. As you say it
would require passing back more information from the range-parsing code.
I can take a stab at making the necessary changes. I'm a bit more
confident now than I was then in changing the range code we have already.

Regards,

--
Paul ~{:-)
pj(at)illuminatedcomputing(dot)com