Horton

Re: unnesting multirange data types

Justin Pryzby <pryzby@telsasoft.com>

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From: Justin Pryzby <pryzby@telsasoft.com>
To: "Jonathan S. Katz" <jkatz@postgresql.org>
Cc: Zhihong Yu <zyu@yugabyte.com>, Alexander Korotkov <aekorotkov@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
Date: 2021-06-13T15:49:07Z
Lists: pgsql-hackers 
On Sun, Jun 13, 2021 at 11:25:05AM -0400, Jonathan S. Katz wrote:
> On 6/13/21 10:57 AM, Zhihong Yu wrote:
> > +/* Turn multirange into a set of ranges */
> > 
> > set of ranges: sequence of ranges
> 
> I believe "set of ranges" is accurate here, as the comparable return is
> a "SETOF rangetype". Sequences are objects unto themselves.
> 

I believe the point was that (in mathematics) a "set" is unordered, and a
sequence is ordered.  Also, a "setof" tuples in postgres can contain
duplicates.

The docs say "The ranges are read out in storage order (ascending).", so I
think this is just a confusion between what "set" means in math vs in postgres.

In postgres, "sequence" usually refers to the object that generarates a
sequence:
| CREATE SEQUENCE creates a new sequence number generator.

-- 
Justin

Commits

  1. Fix small inconsistencies in catalog definition of multirange operators

  2. Revert 29854ee8d1 due to buildfarm failures

  3. Copy-edit text for the pg_terminate_backend() "timeout" parameter.

  4. Add missing pg_description strings for pg_type entries.

  5. Fix pg_description entries for jsonb_to_record() and jsonb_to_recordset().

  6. docs: clarify JSONB operator descriptions

  7. Set procost to 10 for each of the pg_foo_is_visible() functions.

  8. Make use of LATERAL in information_schema.sequences view.

  9. Add pg_trigger_depth() function

  10. Add database comments to template0 and postgres databases, and improve