Date: Fri, 20 Dec 2019 16:13:06 -0300
From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Paul A Jungwirth <pj@illuminatedcomputing.com>
Cc: Pavel Stehule <pavel.stehule@gmail.com>, Jeff Davis <pgsql@j-davis.com>,
	Pgsql Hackers <pgsql-hackers@postgresql.org>
Subject: Re: range_agg
Message-ID: <20191220191306.GA9332@alvherre.pgsql>
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On 2019-Dec-20, Alvaro Herrera wrote:

> I am not convinced that adding TYPTYPE_MULTIRANGE is really necessary.
> Why can't we just treat those types as TYPTYPE_RANGE and distinguish
> them using TYPCATEGORY_MULTIRANGE?  That's what we do for arrays.  I'll
> try to do that next.

I think this can be simplified if we make the the multirange's
pg_type.typelem carry the base range's OID (the link in the other
direction already appears as pg_range.mltrngtypid, though I'd recommend
renaming that to pg_range.rngmultitypid to maintain the "rng" prefix
convention).  Then we can distinguish a multirange from a plain range
easily, both of which have typtype as TYPTYPE_RANGE, because typelem !=
0 in a multi.  That knowledge can be encapsulated easily in
type_is_multirange and pg_dump's getTypes.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services